Scared To Walk Away....

I have been with my boyfriend for four years next month. when we were dating for 6 months he went to jail but right before that he took my virginity. I ended up starting to talk to this really sweet guy & we made a big mistake & i cheated on my bf with this guy (who i later found out was on a lot of drugs at the time we had a "thing") well my bf ended up braking up with me while he was in jail...but once he got out he forgave me & we were fine. at 10months of us dating i found out i was pregnant (i was 15! & he was 17) we were the happiest couple possible...shared our feelings. were in absolute love! when i was 7 months pregnant he got accused of something and went to jail. After missing the birth of our son & sitting in jail for something he didn't do he got out when our son was 6 months old. well although he got found not guilty for that he did violate his probation so right before our son turned one he had to go back to serve just a few months for probation violation. & he then got out & has been out for a full year & no trouble. :) proud of him. like i said we were a happy cute couple. he did live with me for awhile at my parents house but my parents "annoyed" him so he moved back with his mom. after 4 years of being happy...things have changed! He doesn't hit me but he pushes me around. pulls my hair. kicks me when in bed. holds me done. he has choked me before. & idk how to leave. I'm afraid if i leave he will hurt me. or make my life miserable. I also feel like he is only this way because he lives with his mom who is an alcoholic & just dumb...&he has told me before how he is just stressed & takes it out on me. well I told him i'm just as stressed as him trying to find a job. trying to move out. trying to care for a two year old basically on my own. & he said i stress him out too. He goes through my phone. if a random number calls he automatically says who is this? he checks my fb messages....but this past friday it got way outta hand he was throwing pictures at me & yelling at me. & told me to delete my "slutbook" (facebook) and he broke my phone...so now i have no phone. no facebook. and idk where exactly we stand. I took everything my son & i had at his house & brought it back home. I love him with all my heart but i want the man he was like 2 years ago. :) also i should add he cheated on me our first yr of dating because i was a virgin & wasn't sure if i was ready or not. and he says he can't trust me because i cheated on him once...he cheated on me multiple times. He doesn't have his ged or diploma because of getting in trouble so much therefore he can't find a job....so what does he do all day you may ask? he plays call of duty! yeahh. me on the other hand who got pregnant freshman yr of high school I stayed in school & got my diploma last month!! & am now waiting for next month & getting a job. Not sure what i want anymore. do i want to stay with him or leave? i've suffered depression for 2 years now... :/ & he doesn't know.