He is using your children to score points and from what you say, sounds like he isn't really bothered about them. How can any mentally functioning adult say they are washing their hands of a child who has misbehaved, he sounds like he has a few screws loose.
Your children do not need to be in that kind of environment. I'm sure you are aware, that boys who witness their father's violence, are more lilkely to become violent in adult life, than those who do not.
As for him threatening to kill himself, I would personally tell him to go ahead. I expect he is too cowardly to go through with it and it's just another way of him maintaining control of you.
If you don't already, you should probably keep a diary of all these events and police complaints. I know he is their father, but some children are better off without fathers, if they behave in the way your husband is. It can only serve to damage them. If it was me, I wouldn't allow him to see them, until he sorts himself out and behaves like a civilised person around them.
I hope it all works out and that your children aren't too tarnished by all this turmoil.