Help. Getting out of Abusive Relationship

Hello,
I have been dating/ seeing this guy on and off for 4 years. It became really serious in february when I began to work at his buisness with him, quick school and my job to work there. This was in february, In may he told me his female roomate was 3 months pregnant with his child and begged for me to stay because it happend before we starting dating seriously, than in august I found out it happened while we were dating and he still tried to denie it. So on top of that, in the beginnig, he started getting mad that I ha dguy and girl friends and frequently began to ask me about my past. He began then to kind of verbaly abuse me but I wasnt sure how much was too much. Than the physical began it havppened about 5 times over 5 months and lasted about 2 hours long, every time was mainly because he continulously askd me about very private information of all the previous boys i have dated and guys I have been with and the details, When he thought I was lying, he would beat me. He is still living with this female roomate of his as well. In september I started to wake up and realzie what was happening was wrong and have tried to break up with him since, this has been a 3 month long prosses. During this time he convinced me to not speak to m family and that they were the intire problem because I told them what was happening. He has tried to pull me away from them and convince me that he has changed, althought the physical abuse has stopped since I broke down he has since then self mutilated himself and disroy his house. He has also prov en and changed alot and taken me on a vacation to mexico and Toronto and such to show me how amazing he is away from my family and the negativity I am getting from everyone here. For some weird reason I question weather or not leaving him is the right decision, why am I drawn to someone what hurts me so much ! I dont understand and am contemplating going back to him. Whenever we are together it is amazing ! But there are bad times too. I am convinced that no one will ever do the nice things for me he has done or make me feel as Inlove as I am with anyone else. Why do I feel he is the only man I wil ever find to love, is it because it is true? He convices me we are soul mates and are meant to be. Is this true? Are we meant to be apart, is this guy just too dangerous? Will he ever change.. Please help..Will it really be a mistake to go back to him? We have not spoken for 4 days , longest ever, and I am having a unbelievably hard time..