SoTired........I think that, right now, your main priority should be your health, first. You are the children;s mother and they need you. If you get sick, who will take care of them.
Since I don't know the particulars of your situation.....I have a few suggestions that you might think about.
1. I would call your doctor and tell him/her that you are having severe symptoms of anxiety. bordering on panic attacks. Perhaps you could have a prescription to tide you over.
2 An option is to call a woman's shelter and ask them to allow you to stay with them for a few days---and,, with the children, as well. I know of many women who have done that, It is a safe and nurturing environment. You are not under any obligation to stay longer than you want. It will give you a chance to settle yoiurself.
3. What to tell him? When in doubt---tell him the truth (unless you think that he will become physically aggressive).
Say the basics--"-I am physically and mentally exhausted, to the point that I think I am having a mental and physical breakdown.I have to get away for a little while, or I think that I may have to go into the hospital.. I can't go on,". Then take the kids and check into a motel..After you are in the motel----call and talk to a counselor at the local dv center---and, ask about going to the shelter for a few days. If it were me (it isn't) I don't mind telling you that I would tell him that you feel extremely dizzy and your heart is racing and you dont feel normal and you feel like you may be close to having a stroke, Personally, I think you have to do what you have to do to take care of yourself.
I can pretty much gurantee you that he is thinking about where his next hit or drink is coming from.