My friend is always in trouble?

she sleeps around with guys no matter what age/she's 14. yesterday some one punched her in the face for being an idiot. she then decided to post photos of herself on facebook saying don't be a smart *** to randoms. seriously what the hell. it took her being beaten up to realize that. she's so stupid. i don't know what to do when i hand out with her at school i feel like i'm getting labeled for what she does as well. i'm the complete opposite. i've known her for a few years now and it's hard to imagine life without her but at the same token it might be the best thing to turn that imagining real. what do i do?