Girlfriend is going to gay pride? scared she will cheat?

Well my girlfriend is going to gay pride and i dont know why but i hate it when she goes up town or goes to pride because she will get very drunk and you never know what your doing when your drunk. Obviously i never mention anything to her but the feeling inside is awful i feel like ive been stabbed in the stomach because i think of the bad things like people chatting her up, her cheating, meeting someone better. I just want to know if anyone has any advice which make me feel better. ( she hasnt cheated on me before but we were together for 2 years and split up for 6 months and just got back together) ive always had the feeling that people only get totally smashed out of there face when there not happy to try and forget about things.... because everyone can go out and have a good time with a few drinks without going over top right?