<human>: I'm an exchange exchange student studying abroad for 8 months, my girlfriend and I decided to stay together while I was away before I left, and up until now things had been going pretty well. She came out to visit me last year, and I was home over Christmas so I could spend time with her. I go home in 2 weeks for good, and she tells me today that she slept with someone else at a party. I don't know what to do, I'm totally crushed. 

The story was that they were both really drunk and one thing led to another... It tears me apart to think about it... I don't know what I should do. On one hand she was honest enough to tell me that it happened and apologised for it, but on the other hand if I actually want things to work out with this girl, how do I know I can trust her?

Part of me things, well i've only got a couple of weeks left here, lets just run riot and enjoy it, and part of me is thinking that it's only a couple of weeks til I get back so I should just wait and try and make it work. I'm crazy about this girl, I just don't know what I should do in this situation... My mind feels like a wet cake.
I dont know if its worse or better that I know the guy that she cheated with...

I'm still relatively new to reddit, and haven't asked for advice before, but I don't really know who else to turn to.

Thanks in advance.

Can you give me the gist of the text in a nutshell?
<bot>: I've been abroad for 8 months studying, my girlfriend cheated on me with 2 weeks left to go and now I'm a wreck. What do I do?