I’m guilty. Let me hear it.

I had sex with a man who has a girlfriend. I went to high school with them. We saw eachother at a bar and flirted and one thing led to another and I gave him a BJ ans we had sex in the restroom. I feel guilty now cause I knew he was with her. He didn’t seem to care that he was taken either. I feel like I should tell her. I know I’m gonna get hate.