<human>: Summarize the given text in a few sentences.

Recently my girlfriends drinking has gotten out of control. When she starts drinking she always ends up getting blacked out drunk and does really stupid stuff and almost hurts her self when drunk. I tolerated it for a while because we're both in college and I have had my weekends where I do stuff like that. However last week she cheated on me with her girl friend (who is straight and seeing a guy). They made out with eachother while I wasn't there but she told me the next morning and was really apologetic.

I forgave her because she told me right away, was clearly torn up about it, and because I've already seen them make out before we started dating. Also I still really like her. 

Anyways, she's going to be going to a music fest soon with her friends and I'm worried how drunk/high she will get there so I want to ask her to just stay sober for her trip. However I don't want to come off as controlling and I don't want her to not have any fun. I was thinking that maybe I just restrict her to a pint of liquor but I realized that her friends will have alcohol that she could easily take from. So I'm really not sure what to do now.
<bot>: GF gets out of control drunk, made out with her girl friend who is straight, is now going to a music fest and I don't want her to drink.