Help?

Well, you are doing something right already... Asking for help. Go to a therapist and tell someone you trust about this. And please dont cut yourself. It wont help you

First of all, cutting won't help you. Even though you hurt other people, doesn't mean you have to hurt yourself.
Also, you need to act madami positive. See the good side of things. It will change how people act around you and you will find them less annoying.

I had a similar problem when I was younger, and I liked hurting people just to see their reaction. I guess I was lucky and grew out of it because now I can't even imagine hurting anybody.
It sounds like you have Sadism, which just means enjoying pain. But it is good that you are asking for help, it means that you want to stop and you know it's not right.

Please don't cut yourself. You need to go to an adult - a therapist, the school nurse, your parents. They'll be able to help you.