sexual harrasment Sex Crimes, Sex Offenders

hello. AT school i ride the bus. One day while i as on the bus, we were playing around. I was playing around with this girl and my friends drum sticks. I was being sort of rowdy with them, but in no specific way did she tell me "stop" or "please stop that is bothering me." She then grabbed the drumsticks from me and was stepping on my hand. Her full weight was on my hand and i asked her to take it off. When she did not i simply reacted, trying to free my hand from any more injury( i am a bowler and baseball player. Any injury i.e. broken bone can seriously jepordize my skills). I simply slapped her right breast, the only one i could reach. She immediately freed my hand and began kicking me and pulling my hair. Then, she started threataning telling the authorities. I apologized explaining it was simply reaction trying o get my hand free, but she had none of it. Earlier the administration at my school, made it clear anyone who sexually harasses someone will be arrested. I maintain that i was not trying to harass her but trying to free my hand and not cause any more harm to it. My hand is all right. I am woried I may get in trouble. Is there real basis for me to get arrested? I really need help.