Well, he is right about one thing. He isn't good enough for you.
If you are in the United States you have certain legal rights, and he has certain legal responsibilities. Contact a lawyer right away. In Texas he is required to continue paying whatever he paid prior to separation until a legal ruling is made by the court.
He is also going to be required to pay child support on all four children, and in some states he will be required to pay alimony to you.
As to dealing with the anger - you need to be able to vent some of that. Find a counselor if you can. Let your doctor know what is going on too. This stress can't be good on the baby you are carrying.
What kind of relationship do you have with your inlaws? Can you talk to them about how to help your children?
Channel that anger into useful things. Sit down and figure out what you absolutely have to have and what you don't. Look for a good attorney. Do not let them talk you into not fighting for what your children and you need to survive.
My ex literally lost his mind, per doctors, and I had to pick up the pieces. I was not about to give him "standard visitation" given the mental health issues, but I was told, "No judge in Texas will give you better visitation or better child support." A woman in my office said, "Nonsense. Whatever he will sign off on is what you CAN get." So I wrote out my own decree, being careful to be as fair as I could to my ex, and to provide clauses for the judge to fall back on, then sent it to my attorney, who said, "They'll NEVER go for this." said, "If I can get him to sign off on it will they?" He said, "Well, probably." I called my ex and said, "You and I know the truth. The bottom line is, I will protect my children, no matter what. So, are you going to sign this, or are we going to present our evidence in court?" He signed.
As a result I got the standard child support in Texas per child, PLUS, an agreement that he would reimburse 1/2 of all expenses related to medical care, school activities, and special child-related activities such as orchestra and sports. (Generally speaking, child suport does not cover that. It covers, supposedly, what it costs to feed and clothe a child, and that's it.) That he would pay for all house repairs necessary at the time he moved out of the house. (I was willing to fall back on 1/2 of those if I had to). That visitation would NOT be six months here, or 2 weeks there. It would be up to the children (they were old enough), and he could see them whenever they were willing to see him, for as long as they wanted to see him. The "fall back" clause was that if he had any reason to feel this was not working, we could fall back onto the standard Texas visitation arrangements. I also had him sign another arrangement to assist with paying for college tuition if the children go into college right out of high school. Within reasonable limits of course. I asked that the children remain living in the house until the children graduated, and stated, in writing, that if it came to standard "6 months here, 6 months there" visitation, that I would move out for 6 months and let him move in with the children, rather than force them to give up their friends, school, pets, etc. He ended up just giving me the house on the grounds I paid the rest of the mortgage.
This will NOT be easy.
It WILL be possible though.
Once you get through the initial pain and shock, and the anger, you may find that life is easier. No more fighting in the house every day. No more wondering what will happen next. You'll deal with the day to day stress of life the way you dealt with it before, without having to deal with the ex-spouse on top of it.
DO let your church family, friends, family and the school know what is going on. The school counselors and teachers can help your children deal with this.
Don't trash your spouse to your kids.
Do look for a full time job, or insist on a settlement that pays you support up to six months post delivery. Do insist that he pay for 1/2 of all child care related expenses caused by you having to go to work full time.