She cheated while we were doing long distance. Not long after she moved and lived with me. I’m probably the nosiest person on here so one day when I got home from work and she was sleeping, a guy added her on Snapchat, so me being me, I added him back and ask some questions, turns out she was basically in a relationship with this guy at the same time as me and kept lying until I found the truth. It’s been over a year now and it still bothers me, we have tried to talk about it but we end up arguing now, we currently have a baby together. So AITAH for not being able to let it go?