It's amazing to me how laws DON'T protect women and children in this situation in some states. We all assume it does and it's just not the case.
This woman must get a good lawyer. No, she must get a GREAT lawyer. She needs to contact her local NOW chapter and have them recommend one for her.
If she can afford the house on her own, she needs to have the husband removed. To do this, she has to file for divorce, and have the judge attach a restraining order to this. A marshall or the sheriff escorts the husband to the house, stands there while he packs his personal belongings, and escorts him out. Everything else is hammered out in court.
If she can't afford the house, she needs to get a lease on a place she can afford, take the day off from work, get all the help she can, and move every single thing she can out of that house while he's at work. When he gets home she hands him the divorce papers and drive away. Or have him served at work AFTER she leaves the house.
Obviously the children should not be there when this happens.
If he is a psycho she must understand that a piece of paper will not stop a bullet. If this is the case then she'll have to sacrifice her possessions in order to save herself and her children and get the hell out of there.
Good luck to her. Too bad people like this (men and women alike) don't come with warning labels.