This happened in a past relationship.

I had just gotten back in a relationship with a girl just a few weeks prior when she wanted to go to her friends place. I was fine with this (obviously) until I learned it was someone she had hooked up with when we were on a break. I knew that he was still interested in her too, but she promised she was not at all. I told her that she could do what she wanted but that I was very uncomfortable (especially because it was at his place and at night). I also felt a little uncomfortable because she hooked up with him so soon after we went on a break (but she had the right to do what she wanted since we were on a break).

She ended up going and I never found out if anything happened but I did break up with her shortly after. She called me controlling. That wasn’t my intention but I could see how it could come off that way. AITA here?