My girlfriend cheated on me because I wouldn't fuck her.

It was almost 6 months until we had sex. She was a virgin and I was happy to wait. After our first time she told me it was the best feeling she's ever had and she couldn't wait to do it again, and we started having sex a lot more. We got a little too comfortable and she came to spend a weekend with me. We had sex the whole weekend, but on Saturday night I was too tired from work and I just wanted to go to sleep, she wanted to have sex but I didn't so I just went to sleep. The next day she told me she wanted to go home early, I didn't really care and drove her home. The next week she became really distant from me and I tried to talk to her about it but she wouldn't. One day I had enough and I went to talk to her, and she broke down crying and told me that she had cheated on me that night, she told me that she had let her ex kiss and touch her, but didn't have sex, I didn't want to believe her, but she told me that she did it because I didn't want to have sex with her anymore, I didn't know what to say and I told her I needed time and left. She tried to talk to me and apologize but I just hung up on her, she called my parents crying and they told me I should give her a second chance, so yesterday I met with her and she told me that she wanted to work things out and that she would do anything to make me happy again, she tried to do everything I wanted and I just couldn't do it, she offered me sex, she offered to let her parents break their phone, she even offered to let me hit her, but I told her that I just can't forgive her, I'm just in a lot of pain right now and I don't know how to move past this.