While I wouldn't personally recommend threating the boy (lol) I would consider the fact that he may well have something of a crush on you. At that age, as was said previously in this thread, guys of that age have a very hard time expressing their feelings. They don't want to come off sounding unmanly for feeling stuff so they say whats on their mind in a twisted fashion.

Kind of like the "Yes means No, but No can mean yes" expression.

He could be just childish though and is just using you for his personal entertainment.

I would try to talk with him, really reach out and grab his attention somehow. Next time he throws an insult at you, laugh it off and offer to buy him lunch or something. Then, while there tell him that the things he says really does hurt you and you say sometimes you feel like you wish you weren't alive... so I imagine he's not the only person giving you a hard time. Explain to him that you get it from all angles so while you're at your "home" you don't need to get roughed up there, too.

Else, publicly embarrass him. As he walks away distraught, give him a reminder you're not one to be messed with. -shrug- It could work!