Welcome Ellendsburg...The first thing that comes to mind is as you said the '3 happy kids'. I'm hoping either the kids are old enough to understand this man has a problem or too young and in bed by the time he's drunk and ranting.
It doesn't sound like this man has any future plans of changing. It may be in your best interest and of the kids to gather up enough strength to leave. Does he live with you or do you live at his place? Does he just stop over once in a while...Im not sure I understand the arrangement.
I ask because if you are afraid of him make sure you contact local authorites before planning to tell him -especially if he's been drinking and especially if he has weapons in the house. This could be a more serious situation.
He yells at you and you say you're sorry? It doesn't sound like a healthy relationship all around.
If I were you I'd muster up as much strength as I could to split from him. And if you feel the need to get a restraining order -then do so. I speak from experience.