Hi there, me(21M) and my girlfriend(21F) have been together for over 4 years. She had this ex who she lost her virginity to and was really close with up until we got together. I made it clear that I didn't want her talking to him. However, she did end up texting him a couple times over the first couple years of us being together. That was until one night when she was very depressed and texted him. They end up hanging out one night and nothing happens. A couple nights later she feels terrible about what she's done and gets very drunk, ends up texting him, he comes over and they have sex. I feel heart broken that my gf would do something like this to me. We've been together for so long and she ends up doing the worst. She has not texted him since. Her and I are really close and haven't had any issues leading up to this. I still want to be with her but feel torn if I do actually want to be with her. Anybody who has been cheated on and stayed? What should I do? (I don't want to hear "just end it"). I need more than that. Thank you for reading.