Can You Keep A Secret?

Ok.. so one of best friends at school is 'G-Unit' she is most of the time a really nice girl and she can keep a secret. But lately she has been the tell all girl and putting my business out there. I ride the bus with her, we live very close to each other, and we go to the same school. And on top of that, our moms' are  really good friends. If we didn't automatically have to be near each other.. I doubt that we would still be friends. But she told all these kids on the bus about how we made a cover to a song.. and it got kinda personal..  and she told them how personal. But I mean.. we borrow each others clothes and do each others hair. We are kind of like sisters.. but I know that with my own sister I can trust her to not tell anyone.

What should i do???