Troubled and Abusive Relationships Forum - Abusive Boyfriend...but There's Nothing I Can Do

I'm in such big trouble...But I don't know what to do anymore....
About a year and a half ago I started going out with a really sweet guy. He was sensitive, and caring, and passionate, and emotional...The perfect boyfriend. But after a while, he wanted to have sex. I wasn't ready (and i'm still not ready), so I said no. He didn't respond well. He said that we're going out long enough for him to expect this, and that i'm selfish and I need to think about his needs. Though for a long time I thought he was right, I was resolute and didn't give in. He started beating me up after a while, getting more and more aggressive with each time. When I tried to break up with him the beating got so much worse and he forced me to keep going out with him. Last summer I went to camp and somehow let it slip about the situation...The girl told the camp counselor, who called my parents and told them everything. My parents, however, didn't react as I thought they would--they didn't believe me! I had no evidence or marks at the time, and they thought I was making it up to get attention. So it went on, and I kept going out with him. I recently moved to a city about 45 minutes away...But he still calls me every single day, wants to meet me, has "spies" in my school that tell him everything I do and who I hang out with...I feel chained to him. Part of me believes he will change--he wasn't always like this, I think it's more of an anger management thing...But the other part of me wants to be free. I'm sick and tired of making up excuses for the new black eye or the bruises on my stomach. But lately he's been coming to my school and forcing me to be with him, and having his friends talk to me to try and arrange meetings with him. I went to the police, but he was already there when I got there telling them that I was making stuff up to get him in trouble. Though the police believed me, they needed testimony from parents since i'm a minor...And my parents didn't believe me, so they wouldn't testify. I can't tell another adult because then my parents will get ever angrier with me...When they found out I told the police they were really mad. If I even try to break up with him his friends will make sure I regret it. I'm out of answers. He wants me to give him another chance...But i'm so lost. Advice? I would appreciate it beyond your belief.