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

Alright, so on Thursday night, my girlfriend (who is currently abroad and studying in Oxford) and I get into a huge texting argument because she is still mad about things I've done in the past while we weren't dating. I used to go to a lot of raves and do a lot of drugs, but that was in between years we weren't together. 

She has this notion that during this time I was a sex craving maniac who only went to raves to have sex with random girls and that really hurt me because I'm not like that at all. She then goes onto saying that we she thinks we should break up and that really kills me. I know she's drunk, and while it isn't an excuse, it still really hurt. 

Some context about the dating history, we started out in high school for 3 years strong and split when I left for college but were still friends, fast forward to this past summer where we got back together and spent a ton of time with each other and can truly say that I am deeply and madly in love with this girl, pretty sure I always have been. 

Ok back to what happened. So because of the time difference, I'm pretty sure she passes out and I'm about to go to the bars with my buddies. At this point I'm pissed and sad and the whole slew of emotions running through my mind is a mixture for bad behavior. I get talking to this one girl I've talked to in the past, but we aren't really friends (she's a commuter) and she just went through a breakup herself. 

We talk and drink and dance and the more I talked about what happened the angrier and sadder and drunker I get. So I go home with this girl, we have sex, she leaves, and then my girlfriend calls me. She apologizes and we make up with a few hurt feelings. 

But do I tell her about what I did when she gets back or should I tell her now? She has a right to know, I just don't know how to go about this.
<bot>: GF of 4 years and I fight, kinda break up, I sleep(cheat?) on her with someone else. Want to tell her, just not sure when.