Please Help Me...im Losing Him

Hi, I am a 17 year old who is in a long term relationship for 2 years. The past year or so I have hit him but not near as hard as he hits me back...He hits me like I am a man. I do not know what to do. He is always telling me its over when he isn't even serious, he tells me he's droppin out of school, done with everything he's doing. Why must he say all of this when its not even my fault? Well, today he flipped out on me because I wouldn't let him use my headphones. And then !**@! went down from there...He started to shuve me back down on the couch...He told me and promised me awhile back that he'd never hurt me in anyway...And he's broke that and I myself is really hurt to top off how my day b4 v-day and my b-day was...He ruined em both by !**@! and whining...Please help me figure out what I should do....