How to get someone to stop?

Tell him that he needs to stop, if he chooses to continue, go to a school admin or teacher and tell them what's going on. You can get him for physical abuse and possibly sexual harassment. Some schools can issue a type of restraining order I believe so you won't be put in classes together ever.The main thing is you can not tolerate this behavior any longer. Just talk to somebody about it who can help you, okay?

Yes, that is the kind of behavior you can report. Don't worry about "tattling." What he's doing is much worse.

If you feel up to confronting him yourself, you could just react the next time he does it, like yell or something. That should draw attention that there's a problem, so someone in authority might help out. And then tell him that you don't like it and it hurts.

Even if he starts up again, you will be able to get him to stop as long as you keep talking to teachers.