Be tough man, I had bully too in my HS years, and I tried to fought with him. I just ended up being with him and others show respect and fear towards me now. I didn't exactly win the fight since it was stopped before it happened, but I showed him and the others that I don't give up.
I probably shouldn't suggest this but at the point its at I'd suggest putting him in his place. Next time he opens his mouth ball up your fist and hit him as hard as you can right in the mouth. If you do it right he will swallow a majority of his front teeth. Not only will he probably not mess with you again he will end up spending money that insurance won't cover to replace a lot of his missing teeth.