First of all, my prayers are with you. I just finalized my divorce in June. Don't let his threats scare you. No judge would throw you out of your home, at least for right now, since you are pregnant and have other kids. He will more than likely have to pay you temporary spousal support until your divorce is final and he will have to start paying child support immediately. I was getting around 50% of my ex's check during the proceedings. You do need to find an attny. and I had a good one, but he was expensive. His name is John Eck and he is with the firm of Robert Stites in d/t Fort Worth. Check the free legal aid sites and see what you can come up with, then if necessary, call Mr. Eck.
Men know the easiest way to get to a woman is threaten her with taking her children, her home, ect. A good attny. will assure that these threats are not very likely to happen unless you are an axe murderer or something like that. Do NOT listen to his threats. He is such a jerk for leaving you while you are pregnant and any judge will see that as well.
I am so sorry for the loss of your son.
God Bless,
J.