He saw my scars and is being a jerk about it please help?

so there is this boy. It happened about a week ago. So i went to school hoping it was going to be a good day. I was wearing a short sleeved shirt and the stupid boy from before was like "why do you cut yourself are you a freak?" and so I said "no i don't cut just leave me alone" and so he was like "oh yea then where did you get all those scars" and so I replyed very stupid i know but i was nervous so i said "okay at recess I fell over a log in the woods." and so he like "so at recess you fell over a log?" and then i said leave me alone" and he said outloud to the whole cl "She cuts her self shes a freak" i cant belive he said that. Another thing is im scared of boys so yea. I'm afraid he will do it again so i always wear long sleeves and every one lookes at my arms. How can I get that to stop. I don't want to always wear a jacket and long sleeves and i dont want him pointing out all my flaws. how can i get him to leave me alone.