Help me with a school fight?

This kid at my school blind sighted me the other day and beat the s*** out of me with a thousand dirty moves (punch to back of head, foot stomp) Normally I would let it go but the thought that he only did this because he saw my fractured foot as a chance to get a handicap really pisses me off. He's been talking a bunch of s*** since the fight and he says if I look at him funny hes going to KO me. This time, I am going to need dirty moves. I usually fight with honor but not for s like this. I know that the sad truth is I can't beat him fairly if hes being dirty. Please don't tell me not to do it or to rat him out. I just need tips. Thanks.