Do you think he worth staying with or not?

Well, I have a boyfriend that ive been with for about two months. I was in a relationship with him before, but since he didnt treat me right and made me cry almost every night, I dumped him. I was happy all during the time that we were just friends (which was about 7 months) but then I decided to give him another chance since he said he would change, and went back out with him. At first it had seemed like he had changed, but then he started being the same as he once was. He will call me stupid, and say things to hurt my feelings. He doesnt want me to talk to my best guy friend because he says he hates him and whenever I choose to talk to someone else other than him, he gets mad and throws and breaks things. He says that he respects no one, especially not his mother. He treats all those close to him bad, and those that arent close to him, very good. Its very saddening. Im 15 and he's 16 by the way. And his mother thinks that Im trying to hurt him, but thats really not how it is. He is possesive over me and he likes to put me down when Im happy. He says that he can not help how he is and that he has a demon inside of him that he is trying to get rid of but it doesnt seem like he's trying. He says he loves me, but he's never done a thing for me except hurt me. Ive even bought him a psp and given him many of my precious items, but it doesnt seem to change anything. I dont want to break up with him since our paths cross constantly during school and he told me that we couldnt be friends anymore if I broke up with him. I want to still be friends with him no matter what, even if he really isnt a good friend to have. Everyone tells me I need to break off all contact with him because he is a negative influence in my life, but i feel as though he needs a friend and I want to be there for him. I dont want to lose him, but I know I will if i break up with him. Do you think I should give him some more chances or should I just give up?