OK< it has not been that long since you broke up with whats her name, so being depressed for a while after a break up is pretty normal. You do not need to jump into dating if you do not feel you are ready, actually that would probably make it worse on you. As for the girl's that are throwing themselves at your feet, just be honest with them and say that you are not ready since your break up, and you are not looking for dating/girlfriends, but being friends is fine.
As for your group, that is just normal HS shit. Girls follow the girl that the guys want, guys want to get their pee pee wet, and there will always be that manipulative bitch. You can give your friends advice, but 99 percent of the time, they have to learn it on thier own. So if they fall, its not your fault, but as a friend you can help them through whatever.
But, for right now I think you need to focus on you and your life. You need to let your buddies do thier own thing, its just normal high school drama, dont worry about the girls, there will always be girls.