Advice on backstabbers, gossipers, manipulators?

Unfortunately, that's really a common issue. I know when I was in high school I constantly had the same problem. You've got to find some good friends, even if they don't go to the same school. Every person needs a honest group of friends to vent to and have fun with. I went to a school in a town Pop. 700+, and my cl had 14 in it. The gossip & betrayal was very difficult to deal with. Just look forward to the fact in a few years you'll probably never see them again, and that you're more mature than them. Also, I learned to keep my mouth shut. They'll come up with mean things to say all by themselves, don't add fuel to the fire. Good luck & I hope things get better!