Second pregnancy but in a shitty relationship.

So my so called boyfriend and I have been together for three years. I left him two years ago because he cause he was being abusive towards me, emotionally and physically. He never hit me tho. During our break up I was still seeing him. He would check up on me and ask me if I was having sex with anyone else and I would say no because I wasn't. A month later I got pregnant with my son. I told him that I'm pregnant and he said is it mine. I was appalled. Through out that pregnancy he doubted his son unit he was born. He stopped questioning it. Fast forward now I'm pregnant the second time and I told him and he didn't believe me. I hade the stick in his face. He didn't see anything and I said look closer and he said oh. I was like ya. Neither of us were excited about it. I wish I was but I'm not. He blamed me for not going on bc and I blamed his for not using a condom. It's both out fault for not being careful. When I went went for my ultrasound and came back he asked me who have I been having sex with and I said no one. He said he doesn't know how this happened but we never have sex. We have sex once or twice a blue moon. He's such an asshole. He like to call name when he gets mad and doesn't reframe himself from calling me names. We argue in front of our son and I don't like it. Our son it 1. This relationship has been shit ever since we got back together. I want to leave him but I don't know to go about it. He won't let me take our son if I try. My car is needing the brakes done and he won't let me use his car so I'm stuck. I hate him so much I don't want him a live anymore. I know that sounds horrible but that's the way I feel. I've told him that I don't want him to be in the delivery room and I don't want the baby to have his last name. He said that if the baby doesn't his last name then he won't take care of it. I was like fine I guess your going to be paying for child support then. He said not if there is not proof that I'm the father. I said to him that I will get a paternity test done and you will be paying for child support. He tells me that I'm not a good mom and that I don't feed my son . Mind you I work graveyard and he works from home. I've seen a lot of men work from home and take care of their kids and he always has excuses for for everything and I'm sick of it. I can do this on my own. I really don't need him. He makes me want to talk to my ex again which I am highly considering. But who wants a pregnant woman. I just want to live my life with out him.I need help with this one.