How do I get out of an abusive relationship?

I've been with my boyfriend over 3 years. He cheated on me and the woman is now pregnant. He is physically and mentally abusive towards me. I have attempted to talk with him in order to resolve our issues; however, he never wants to talk and often blames me for everything.I'm always there when he needs my help. He tells me although I help him doesn't mean that I am a good person. He always discredits me as a woman and it's hurtful. I spend most day crying and feeling lonely. I am unhappy and unsure of what I need to do.