You just need to focus on important things in life.
Yeah, at your age things are going to get stressful, I'm only 14, so yeah I know.
We freak out at anything and you just have to get on with it because it's a phase of your life you might as well make the most of.
Like Bev said, take up boxing, vent your anger.
I suggest forgetting those 'friends' of yours, because they don't sound like friends at all to me!
goodluck.