This kid wants to fight me help?

I don't fight unless in self defense (even tho i pro wouldn't). This kid Logan wants to fight me bc his ***** Zack doesn't like me bc i yelled at him because he was all over my gf i'm 15 he is 13 and he threatined to light my pants on fire lol but when he saw me he pussed out.. What do I do if he hits me? ((Im 5'7 115) he is (5'5 125) I heard he isn't tough but i m not scared because I m a black belt in bjj and been boxing for a year or two and have beating kids twice my size in a sparring fight))