My girlfriend of 5 years was sleeping with someone I know during a 2 week breakup in Emotions and Feelings Posted September 27, 2017 I disagree. He was playing games with her and it backfired. However, OP, that doesn't mean that you can't feel terrible about what happened. I do think you need to see a therapist to get over this. After 4 years, I don't think you can move past this on your own. Seeing a therapist would be the best for you, I think. Does your girlfriend know how you feel? I also find it concerning that you can talk about your girlfriend being "pounded," like she's just some sex object. Please see a therapist, OP. I’m not trying to be rude! It’s just the feeling I have.. I know it was a hot and heavy relationship with this guy that I know as I saw Marks on all over her breast during my daughters baseball pizza party. The clothes she wore to the party said it all. Maybe going to town would have been more appropriate!! Anyways, how do I let it go!! Her brother is friends with the dude! It’s weird now!