I doubt she is putting on an act for the children. They are old enough to have figured out the dysfunction...after all, they are living it. IMO it's more likely she thinks this guy will go even further off the deep end if she divorces him.
I feel sorry for her but I can't imagine this can go on much longer. The situation has got to be unbearable.
If he's THIS awful in public...how is he in private? So unless this is all just an "act" and she's in on this, with him, she's as sick as he is, for staying with him!
And yes, their children aren't babies or toddlers; they're absolutely old enough to see and understand what has been going on.