So tired of being in a abusive unloving marriage

I am 34 years old. I have been with my husband since I was 19. We have to great kids. But unfortunately that's the only thing that is great in our relationship. I have changed a lot in the years reinforcing very hard to be what he wants but it is never enough. In the begining he said he loved me just the way I was but that quickly changed as soon as I got pregnant. I was told at 16 that I would never be able to have children. So when I got pregnant I thought that must mean that I was supposed to be with him. That maybe he would be the love I was destined to find and be happy forever. But other than the happiness I have got from my children that is it. He puts me down ever chance he gets he has physically hurt me more times than I can remember. If he doesn't want to hear what I have to say then he tells me to shut up. And if I don't he will shut me up. I don't have any friends or family he made sure of that years ago so now I'm all alone with no one to help me. I don't even have anyone that I can trust to talk to. He tells me he reinforcing to turn even my children against me. And he says then I will have no one at all. I'm only aloud out of the house to take the children to and from school and the store on my way home with the children. When I did go to work that didn't work out for me so well. He constantly accused me of cheating even though I was not. So I had to quit to avoid being killed.He has always accused me of cheating even though I never have ever. How ever I have found he has been sending emails to whores on the internet. He says that he loves me but he sure as hell does not show it.I don't know what to do.