I am going mad behind the wrong person. Can't control myself

8 months ago I became friends with this girl in college. I thought she was pretty cool and we had a lot of similarities. We became quite close and used to share details of our life. I was really having fun with spending time with her. (We had to do a project together so used to spend a lot of time together). She would constantly cry about all her problems in life and I was there to listen to all of it, give her all the advice she needed. I used to type long ass texts to her and tried my best to give a solution for all her problems. I thought of her as a good friend and had no problem doing all this. Then I also started to have feelings for her. I have never revealed it her. (She would talk to me about how she liked another guy and I was well giving her advice). Anyways we were really good friends by the end of finishing our project. Then after the project, she didn't use to talk much with me. During the college break, after the break. She would only come up to me if she wanted to talk about the project or had any other work (Seeing that we were good friends, I decided to do my final project with her--big mistake). I was really pissed by her selfish behavior. I spoke to her about it. I have spoken to her about this thing 4 times or so. The last time she straight up declined that she was ever being mean to me. Once I typed a long ass message just to point how various instances of her being mean to me. At that time she would say Ill try to change myself. Currently we aren't talking except for any work. I told her I need her to accept that she was being mean and give me a good reason for her behavior. I told her not to talk to me before that. I don't know what I am doing is right or not. She just wanted me to forget all this and start afresh. ow I am I supposed to do that ? After someone hurts you so much, how can I just forget about if and act as if nothing happened. But I am getting too obsessed with her. I mean she isn't even worth it. She has not done anything great for me as a friend that I am crying over it. She was not there for me when I needed her ( while I was always there for her). I just feel that someplace I have gone wrong. It's like a feeling of guilt. I have a tendency to expect a lot from girls I like so I think I might be making the same mistake. But thinking about it rationally, I don't think I am expecting much. I just need her to be normal with me. Talk about stuff other than work. Considering how good of a friend I have been to her, I don't think what I am expecting is wrong. The worst part is, during all this time when we weren't talking, she never even cared enough to ask me what was wrong. Since she was being mean, I kind of stopped talking to her from my end. But she never cared enough to ask me about it. I have always cared about her in the smallest of thing and this is what I get. I don't know what to do now. I tried talking to her so many times. What more can I do. Deep down I don't want this friendship to end because I have invested so much time in all this. I also can't forget all of it and act as if nothing happened. Worst thing is I feel so bad and feel like crying while she is happy living her life. She seems to enjoy a lot. Right now just seeing her laugh and be happy makes me feel so bad about myself. I have so engrossed in all this, I haven't been happy for a long time. I know I should't be feeling sad seeing someone else happy (Especially when you like them). Also she has getting close to so many of my other friends. Talking too much with them and all. I just makes me jealous and I feel really low about myself. I think I did something wrong so she isn't friends with me. Please help me out. I know I shouldn't be caring at all about her and live my life alone but I just can't do it. I constantly think about it all day. I am going mad. Sorry for the long post.