Flirty texts at night, and lies

Hi, I'm 22 years old and been dating my gf for 2 1/2 yrs. I noticed something different about her she looked diferent going to work like excited . She works as a waiter at nights . Well from Tuesday till Saturday she worked all night I went to work around 9 got home at 5 I never saw her she came home past 10 every night and latest 11:30 which she usually only come homes that late once a week maybe that . All week I was sad I felt that she was cheating on me but had no way to prove it . She spent more money then usual but had no excuses for it and also she picked up extra shifts at work. I stayed up waiting till around 11 . I would sit outside and wait for her for hours she usually gets off around 9 but I would just give up . I really didn't talk to her that week because I was crying a lot and didn't want to show her so I was really silent for that week. She would ask for the phone at night so she could se the alarm and plug it on her side .usually sits on the night stand but she wanted it on her side. Well Sunday morning I ask for the phone she has it in her purse and checks it before she gives it to me , I tell her I'm going to call my mom , then I go to msgs and no inbox msgs and she didn't know how to delete these outgoing msgs so I ask her who's she's been texting at 12am -5am there was no way for me to see what he said but it looked on her end flirty she says they were just friends and when she was at school she really went to the horse stables with him . So I am pissed I want to leave she lied to me all week I even asked her on Friday If she only loved me and she said yes . She cried and begged me to stay then a month later she after I asked frequently she said he liked her and he would tell her she was hot and wanted her to come over and he wanted to do stuff with her and leave me . She txtd him this examples . I was being a asshole one night another mag we might break up etc so I don't know if she was attracted to him and did stuff with him he's 6'1 good looking guy and when I saw him I believed she did something with him. FYI there co workers she also says that week she felt that I didn't like her anymore and that are love was fading away . So I don't know what to believe she crazy sexually so I could see her doing something she has never talked to anyone but me for our whole relationship very trustworthy that's why I had all the trust in the world in her . This happened about 3 months ago but it brought me so close to her I don't know what to do , I wasn't as good to her back then now I open the door more, more date nights , We play tennis together, i feel that sex has never been more passionate . We hold each other when we sleep I spend every second I can with her no matter what . She is my dream girl beautiful smart funny caring I would want her to be the mother of my kids . I love this girl so much!! My real question is I don't know what to do I feel that she cheated on me she denies it I just don't know what to believe I feel that she lying just because if she told me the truth I would break up with her , also I feel I wasn't the boyfriend I should of been to here before she deserved better . It's just hard I think about it a lot and have no one to talk about it she hates talking about it and ends up yelling . Just hoping on advice and comment . Sorry if this is long and has poor grammar typed on a iPhone so it's really small , thanks

The past is the past. And it seems like things are going great now! Don't let the past being this relationship down. You love her and you should accept her faults no matter what. But in the end she choose you! So you shouldn't worry