Dream of girlfriend, sexual

Every year my girlfriend goes to a camp where she is a counsellor. I've heard things about the camp about sexual behaviour. I trust my girlfriend however, but I recently had a dream that she, and I were at that camp, and I walked into a room where she was in bed with another guy. She got out of bed like she didn't seem to care, and walked out into a room where there was a group of people and put on her clothes, and everyone looking at her of course. I'm standing right by her the whole time, and I tell her to come with me into a room where we could talk. I ask her what she was doing, sleeping with other people and showing herself off, and she was nothing but mean to me, saying things like, "I don't care, no body likes me if I'm not sleeping around and acting like this." And being mean to me like I've never seen. The dream was so vivid though, where it made me wake up crying. Anything you can tell me would be appreciated!