My long-distance girlfriend slept with her cousin, and now she says she wishes it never happened and doesn't want to talk about it as it makes her feel uncomfortable.

Me and my long distance girlfriend were both virgins and never had any sexual experience before and we wanted to explore eachothers bodies and take eachother's virginity ,everything was going well. We were supposed to meet eachother a month later. But few days into that she tells me she was drunk and she let her cousin touch her ,kiss her ,and basically take off her virginity , i've been traumatized ever since she told me this ,it's like something that will be there in my mind forever regardless of anything. Because she said she loved me and she betrayed me by sleeping with her cousin without even thinking about it. Now she says it was all an accident and she still loves me and wants to get intimate with me and even live with me. It's hard for me to think about getting physical with her or anyone whatsoever because of the trauma. I also love her very much but I wanna talk to her about all of that ,but she just says she wishes all of that never happened ,she says she loves her cousin as a brother and family,and it makes her feel uncomfortable thinking about all that knowing she cannot change what happened, I feel very insecure especially when she is in contact with her cousin, I introspect with myself if she will be able to love me after the time she spent with her cousin(btw her cousin kept asking her for favours and she kept agreeing to them as she was helpless). She just asks me to forget this if I want everything to be fine.