How do I get my friend to keep her mouth shut?

One of my friends has recently got in with another crowd who kinda look down on me because they're the 'in crowd' and we I suppose are in the middle somewhere...stupid stereotypes I know. This is a really immature question but it's bothering me all the same. Anyway, this friend has started going out a lot and gets drunk on weekends with them...I told her some stuff a couple of years ago, you know the type of gossip that 13 year olds spread, like family stuff, guys I liked, embarring moments in junior school, etc. Anyway, she keeps the family stuff relatively quiet because she knows that you just DONT joke about it, so I'm less worried about that as she probably wouldn't bring it up to any of them...she's not that bad of a friend!! But the more 'gossipy' stuff I told her...she has teased me about, and I'm terrified that she'll tell her new friends. Especially because I see them a lot in lessons and on buses and trams, and they're the sort of people that if they get to know some stuff they'll tease. So I'm basically scared of them knowing what I have told my friend. She's a good enough friend not to tell them anything...unless she's drunk...and this happens a lot... so do you think I should confront her? Ask her not to tell these lot anything about what I've told her? Or just ride it out, after all I only have 1 1/2 years left of school then I will (hopefully) be moving away from them so if they know anything it doesn't matter? Just I hate school that much anyway that the thought of them knowing things about me just drives me insane! Please help, advice? Yes I know it's immature but it's really getting to me ! Thank you x