<human>: Can you give me a shortened version of the text?

I've been hooking up, eventually leading to sex, with this girl for about a month now. She's not the most attractive girl in the world, and definitely doesnt dress like she gives a fuck about anything. I have no idea why I did what I did, but that's besides the point. Point is, she brought her boyfriend to class today. We're in a group and have to be in the group, I got up and left, almost gagged. She told me last night what was happening, I knew I would be an ass, no matter how hard I try it always comes out in situations like this (sorry not trying to make excuses). She brought him anyways, guy doesn't even know what's going on.

I have every right to be mad at her right now, right? We both know we were interested in eachother, but when I found out I got invited to my first choice next semester, I stopped whatever was happening. This was a week ago, I let the sex drag on for an extra two weeks.
<bot>: The girl I've been having casual sex with decided to bring her boyfriend into class today. Am I right to be mad?