Thinking of leaving my so

Currently I am 17 weeks pregnant. I have been with my so for almost 2 years. Right now I am thinking of leaving him. Lately we have been constantly fighting and it's been so stressful. He already has two children (4&5) which I love but he is making things horrible. He has told me to leave our home multiple times and told me that I act like his children's mother. (She is insane and he hates her with a passion) He is going through the a custody battle with her and when he gets bad news or fights with her it gets taken out on me. Being pregnant I do have some mood swings, and when I have them he just fights with me more. He tells me it's not an excuse to be a bitch. I just don't honestly know what to do and I'm so torn. I take care of his children, I take them and pick them up from daycare every week even on my off days. I'm just rambling now. It's just getting harder in me because I don't want to share a child with someone who is ok with telling me to get out of his life. I know I've already made that choice and that I have to deal with it, but I don't know if I should leave for good. Advice please.