<human>: Can you condense the text into a few key points?

I'll try to keep this short. My boyfriend broke up with me about a month ago, and we just decided Saturday that we wanted to work things out and try again. Everything seemed like it was going really well (doesn't it always?) until last night he dropped the bomb that he slept with another girl while he was really drunk. I know he didn't do anything wrong or "against the rules", but the fact that I was doing all I could just to make it through the day and he felt okay enough to fuck another girl really stings. He says he regrets it and he seemed genuinely sorry. Also I should mention that I'm not mad, since we were broken up and everything, I'm just disappointed and hurt. It feels like our relationship couldn't have meant as much to him as it does to me if he felt like he could be with someone else so soon after leaving me. 

I just want to move on. I want to know how to stop images of him with another woman from popping up in my mind. If any of you have gone through something similar, I would really like to know what you did to cope and if you ever overcame it.
<bot>: Boyfriend left me about a month ago and slept with someone else while we were broken up. I know he didn't technically do anything wrong, but I'm still hurt. How do I move past it?