How do I stop myself from wanting to drink again?

Ok, so the yesterday my cousin came over along with one of my best friends, and we were pretty bored…so they suggested in a joking manner that we get drunk and try to play a game, but that soon changed from being a joke to actually happening. at first, I said no, I am not drinking, thats stupid…but then my cousin gave me some of his drink, and it was really good…so I was debating whether I should get some or not. and I guess I caved, and had a couple cups of it, and apparently I got a little drunk. and I admit, it was poor judgment…I feel so stupid for it. I woke up today feeling like crap. but I didnt tell anybody I drank, because if my parents find out they would kill me, and if my girlfriend found out she would most likely break up with me, and I assured her that I would never drink, and that I wouldnt be that stupid. and now I did, and I feel like a complete a$$…but today, I felt pretty stressed, and upset. and I wanted to drink again, of course I didnt, because I dont want to do that again, I realize it was a stupid mistake that I dont want to make again. but, I dont know what to do, because I know this is going to keep happening, im going to get stressed and all im going to want to do is drink a lot, and I know thats not the way to go. so there has to be a way I can stop myself from wanting to do it again, so is there any advice anybody can give me? it would be greatly appreciated. thanks