Husband with PTSD

Amanda • I`m going through a separation. I have a 5 yr old. Had one ectopic pregnancy back in December. Pregnant with baby #2!!
My husband and I have only been married for 6 months. Everything seemed great at first. I got pregnant the first month of trying, and ever since then, he has either pulled my hair, choked me or punched the walls during our arguments. I am currently 20 weeks pregnant and tonight we got into a real bad one. He ended up with punching me in the head on accident while he was trying to aim at the door I was up against. He says he has never done this to anyone before and he doesn't know where its all coming from. He says he wants help, and he says he needs my help, but idk how to help him. He acknowledges his abusive behaviors. He has been in the army for 14 years and just got out today, so I know he has been stressing about work and how he's gonna provide for us. I do have a 5 yr old son that adores him . he is a good dad, and he before the arguments get bad, he does try to leave to get away for a while, but I say something under my breath and he hears it and goes off. He has never hit ms until tonight. He felt extremely bad for it. What can I do? I am not leaving him because I married him for the good and the bad. I know he's a good guy, but I guess a part of me fears it getting worse. Any advice ?