I believe the woman I love cheated on me, but I need outside help

Hello all, thank you for reading this. I don't have many friends, so I don't have anyone to speak to about this issue, so I came on here. I'm a 20 year old male who works full time as a machine operator, and my girlfriend was a 19 year old who worked two jobs. We were together almost 4 years, and we were working hard to save up for an apartment together. This was a very deep relationship, over time we overcame our trust issues and stayed that way, we took each others virginity and it was a very special moment, and she would even constantly write me letters telling me how much she loved me. Two months ago, she told me she wanted to break up over a text message, then told me to come over the next day and ignored me the rest of that day. Because i was alone all day with the feelings she left me, i was very emotional, i couldn't get out of bed. When i got to her house, she wanted to talk to me about things i was doing wrong, but like an idiot i was far too emotional and i told her we were breaking up just like she wanted. I didn't understand why she'd want to break up because of small issues. These issues were that i wouldn't go to a fare with her because it was at 5pm and i work night shift. I also wouldn't go to her dads parties because he disrespected me and I was still getting over it. Other issues were that i would change my sleep schedule for other people and not her, which was not true, as i only saw my one friend roughly once every 2 months and he has the same sleep schedule i do. A couple days into the break, I couldn't stop thinking of her, she was my life. I got a hold of her and told her i wanted to fix this. I went to her house again, and this time i had her talk, and i told her the things i said above. I never change my sleep schedule, i had issues with her dad and i needed time. But i did something wrong, I told her if she wanted to go out more she should plan things herself. That was wrong of me, i should take responsibility and plan things that she wants, its my job as a boyfriend. After the talk, we were together again, and we made love, better than we had in a long time, because of how long we were apart. After that though, she was very distant, and wouldn't come close to me. Later in the week, she told me she didn't want me near her, then told me she needed time to herself. For hours i tried to talk to her and tell her we could work it out, talk everything out like always, fix the problem, but in the end she told me she didn't want to talk and wanted to be alone. I yelled on the phone, for the first time in our relationship. I wasn't insulting her, i was yelling about how alone she was making me feel and that for everything i've done for her in the relationship, i at least deserve to talk to you and fix my mistakes. The next day, she told me she missed me with all of her heart and she couldn't live without me, that she saw she was being unfair and that she wanted to call me again that night just to hear my voice. I was very happy, and we talked that night. She told me her sister was coming down for the week, and that she might not be able to talk much, and i understood. I told her she could have a couple days to herself and enjoy time with her sister. Her sister left on a Thursday, and by the time Friday rolled around i had heard nothing so i called twice times and sent a text asking what was wrong. When Saturday rolled around, i was terrified, what if she got in a crash taking her sister home? I drove out at 2am to her house, and her car was still there. She ignored me completely up until the next Tuesday. The first thing she said to me after ignoring me for a week? I need space. I yelled again, for playing with my feelings and making me feel it was all alright just to abandon me. I said mean things, I told her she wasn't a princess and doesn't deserve some amazing treatment while throwing me in the dirt. Everything i said was just me being emotional from being ignored for a week, it wasn't me talking. She came over right after, my request. She walked in and i couldn't stop crying, i was really hurt by what she did. I apologized to her for yelling, it wasn't right and i knew that. I then had her talk again, this time i told her that i would hang out with her dad whenever she wanted, that I would make plans and take her places like the boyfriend she deserved. That i was going to make everything better. She never said sorry for what she did, but i didn't care. We made love again, and laid there for hours together, and i was finally happy things were going to work out. After this, she only replied to my messages with one word texts, like "cool" or "yeah". This was way different then what we're used to, and is usually indicating that something is wrong. I asked her why she was texting different, and she said she wasn't. I really needed her there for me, to help me recover from ignoring me, and I wanted to know why she was acting different, and she actually fought with me, argued for little to no reason, then at the end, she said all we do is fight, and that she wants space. I wasn't going to let her have space after she ignored me for a week, I was standing my ground and i refused to do that for her until she made up her mistakes to me. I already told her i was going to fix our issues, but she continued to say she wanted space. My mind wandered at this point, was it another guy? I asked her that, and she said no. She was never attracted to other men, not in the weird lying sort of way, she just didn't like a lot of them, she had 2 ex's and one cheated while the other tried to force himself on her. Back on topic, when she said she wanted space again, i told her we needed to have another talk, and i was going to spill my heart out in this talk. She refused, and she told me to stay away from her house, because she was lying to her family that our relationship was still broke up. She then told me as far as she was concerned, we weren't together. All the suffering i did in those months, the way i made love to her with all of my heart, then i realize she had no intention of fixing anything. I wrote a 12 page letter, got all of the stuff she gave me and put it in a box, and left it at her house. She refused to talk to me, so i broke up with her with a letter, because i refused to do it with a text message. My letter said the things i wanted to say in person, about how much she meant to me, that she was my one and only forever, but she was pushing me away and despite loving her I really couldn't take it anymore, it was over a month straight of her arguing and never saying i love you, while i was trying so hard to fix it all, fix the mistakes i made, fix the mistakes she made. She gave me a hand made scrapbook at the beginning of the year, telling me inside how much she couldn't wait to build our future together and that we could add photos to it as we aged. It was the most precious gift I've ever gotten in my life, and i was going to propose to her this November, because i knew she was the one. I kept the scrapbook, because deep down I knew i didn't want to leave her. In the letter, i told her i wouldn't talk to her, just like she did to me. After she read the letter, she sent me a message saying i was the most important person in her life, and she couldn't imagine her future without me, i was all she thought about. It hurt me, but i stuck by my guns and didn't respond, I wanted her to have time to see if she really loved me. I didn't want the break up, i loved her way too much to give up, but nothing was working, i couldn't talk to her. Two days after the break up, she begged me to help her, because she had no one to go to. I did, I went to her, and i helped her deal with issues her father was having. I couldn't leave her alone, she was too important to me to abandon her when she needed help. After i helped her through it, she asked if we would ever get back together. I said yes, and she was beyond happy. She told me she realized that i wanted to fix everything, and that she just didn't give me a chance and it was wrong of her, but now she understood and was going to make me feel like the happiest man in the world, she would make it up to me with everything she has. She told me she couldn't wait to marry me and have the children we always talked about, and that it was all she thought about, and she was grateful i was giving her another chance to prove herself. She was finally back to the way she was, talking to me, letting us work it out, and we both promised and agreed that we love each other and would get back together. I asked her the next time i could see her, and she told me she didn't have a day off for roughly 2 weeks. It was a long wait, but i finally got to see my sweetheart again. When she came over, after some talking and asking questions, she told me she had sex with another man after we had the talk after the break up. She says she didn't cheat, that we technically weren't together, but in reality, just like i said above, we had agreed we were getting back together, we agreed we loved each other, we promised we would make our relationship strong again. And after saying all of those things, days later she went and had sex with someone else. As i said before, we took each others virginity, it was very special to both of us. She always told me she couldn't imagine doing it with someone else, doing it with someone she doesn't love, and i agreed, she was so different, and i loved that about her. When she told me what she did, i yelled and told her to leave, then began texting her. I needed to understand what was happening. I was experiencing heavy denial, anger, and depression, and i had to have some type of closure. She didn't cooperate much, but in the end i got the details i wanted to know. She was texting him behind my back, and she knew full well that he liked her. She said she texted him because it made her feel special. After we had our talk and decided to get back together, she used time she could of spent with me, told him that she was single, and went to his house and had sex with him. They did not use a condom. She also went through with it the entire way, let him finish and everything. I asked these things because I was trying to forgive her. If he persuaded her to do it, if she used a condom, if she regretted it after knowing i still loved her and stopped it halfway through, i could have forgiven her. She tells me she thought of me the entire time, that it didn't feel right if it wasn't with the man you love. Her reason that it was okay is that I never spent time with her. Her jobs gave her off two days a week, and on those days i drove over immediately after work and spent the entire day with her. She was upset that we didn't go out and do anything, but money was hard after we both bought new cars, and i told her it would change. Spending time with her was all i ever looked forward to, and I kissed her plenty, cuddled her, watched her shows, and made love to her every time. Hearing her reason that i never spent time with her just because we didn't go out and do things is just insulting, considering she could of sat me down and told me it was an issue. I told her this, that communication is very important, and she told me she shouldn't have to tell me to spend time with my girlfriend, when i always did the first opportunity I had. She went behind my back, and the moment she had the chance, told him she wanted to have sex, despite knowing full well i still loved her and our relationship was going to start again in a week, stronger than ever. She also knew i was going to propose to her, as it was in the letter. I even expected this when this whole issue started months ago when i asked her if it was another guy, and she lied and said no. She says it was a mistake, that she really likes him but she'd give him up any day for me. I don't understand it, she knew she was getting me back, why would she do that if she loved me more? She begged me, she said the same things she said before she had sex with him, telling me she can't imagine life with anyone else and that all she see's is me in her future, that she won't let me get away just because she made one mistake. She said that if i truly love her, then i will forgive her and give her one final chance. Despite all of that, she then said that she didn't cheat, and that it is unrealistic to have sex with only one person. Of course that is true, but it hurt me to hear that from her. Sex is very special to me, I believe you should only do it with the person you love, I have no interest in doing it just for the sensation, and she was always the exact same way. Something changed about her, and she will not admit it. I told her that i refuse to have a relationship where i have to go through her phone like a horny teenager and watch the people she talks to. I was never the jealous type, and i refuse to live a relationship like that. It would also be hard to touch her again. You may consider it childish, and honestly I agree, but taking each others virginity and having the bond for 4 years was very important to both of us, we were each others one and only, and the literal first and only chance she had, she cut that bond with no hesitation. She spent all of that time saying she wanted to be alone, but when she had it, she instantly went to another man who didn't love her, time that could of been spent with me. I told her she betrayed me in every way possible, with the refusing to talk to me, ignoring me while i was worried sick, and overall making my life a living hell despite me trying to fix it. Then realizing she was going behind my back and had sex with someone else while refusing to acknowledge that it was cheating when she knew our relationship was starting up again. I could of yelled when i told her this, tell her how screwed up everything she's done to me was, but i was as polite as i could be, i told her she betrayed me, broke several promises, and went behind my back, destroying both my trust entirely and my respect for her, and that i was going to move on and find someone who wants to touch me and only me, and be happy with that, then i said goodbye and thanked her for the years of love she gave me. She said f me for making her cry, because she's fighting so hard for me and i clearly don't love her, because if i did then i would give her another shot, then told me she can't describe in words how much she hates me for leaving her. Did i do the right thing? Cheating is a relative term, if you want to look at technicalities, then we weren't together and she screwed another guy. If that's all it was, as hard as it would be, i could forgive her. The problem is that she was texting him behind my back, and we BOTH agreed we were getting back together stronger than ever, and she still went out and had sex with someone she doesn't love. With those two things combined, I consider that cheating. Every bone in my body wants to tell her I'll try to forgive her and we could try again, but I feel i would never be happy, she's changed so much and she broke everything that made me fall in love with her to begin with. It really is the most revolting and heartless thing to believe I was sitting at home looking at the scrapbook of our memories, excited to start again, while she was having sex with another man. I'm lost in a sea of thoughts about what i should do, can you guys help me? Thank you so much for reading.

You describe your relationship as deep and meaningful but your GF viewed it different. Her actions should tell you where you stand with her and it's obvious that her words mean very little. Yes, she did cheat and it's this betrayal and her somewhat blase attitude about it all which hurts and cuts you the most. For you to remain with your GF, means that you have to learn to trust her again, after forgiving her first, which she just expects you to do after betraying you in the first place! After 4 years, you're better off using this energy and effort to move on from her and get on with your life. Most respectfully, you need to share your life with someone who has your values and who supports and respects you in every way and gives you predictability in your relationship rather than attempt to deal with unacceptable behavior and it's consequences. Give your heart to someone who has the NEED to keep it safe. Why bother attempting to repair a relationship which offers little (if any) security however special it was at the beginning.