Lilypuss,
Re your comments:-
"I will talk to him tonight about everything. I'm not letting this go this time".
He will talk you down and blame you yet again if you do this. Its a waste of your time.
"I'm hoping that if he can talk to someone about his own issues that this might help"
He does not want help and you're frankly the last person who can help him. You cannot make him seek help, he thought that counselling was a waste of time and blamed you for it all.
"I know I'm clutching at straws a bit, but I'm not ready to tell him to leave".
If you were to tell him to leave are you afraid of his reaction?. Would he strike you again?. Is that what you're afraid of.
Yes you are clutching at straws and no you are not ready to leave - yet. But stalling tactics and delaying things further does not help you or your children who still see all this on a regular basis. What are they being taught here by the two of you about relationships?.
"I feel I need to give him a chance to help himself"
Why do you feel like that?. You are not responsible for him. You cannot rescue nor fix him nor should you actually attempt to.
"He is a good dad lots of the time (I really know how stupid this looks with respect to the above - but I can't see things in such black and white terms yet)".
You need to start seeing things in such terms and snap out of your own denial and disbelief. If he is disrespecting the mother of his children, threatens them with violence and hits you (I note he has hit you in the past, there's nothing stopping him from doing that again) then he is patently not a good Dad at all is he?. This is a view often expressed by women in abusive relationships because they themselves cannot think of anything positive whatsoever to say about their man.
You have spent two decades with this man, please do not put your self through any more of this for your sake as well as that of your children. It is perhaps only when you are fully away from him will you realise the full extent of his abusive treatment.