Hello there, may I help you? I have a different perspective on this problem, trying to put myself in your husbands shoes, he is playing games here, trying to score points and is obviously not giving any consideration to the damage he is doing to your relattionship with your children as a result of his hard words, but he is also brain washing them into thinking that you are the bad one who is to blame in all of this.
Your children are at a volatile age where they will be easily lead by what they are told. It is important that you don't end up embarking on a cat and mouse game here. Don't say a bad word about the children's father to them. When they come home and are aggressive and difficult they will be looking for a reaction. It is important not to give one.
Children will eventually work out for themselves who and what they believe but you may have to bear the brunt of there cruel words and bad behavior for now. It is important that you don't discuss anything that went on or currently is going on with you and the children's Father. If they ask questions the answer is simply "That is between me and Daddy". They are old enough to reason with and also to understand that the way they behave when they come home upsets you and you so look forward to seeing them when they have been at Daddy's...etc etc.
I don't think there is any point in trying to pursue talking with the children's Father about what he is saying to them when he sees them, as he is clearly not thinking straight and not putting their feelings first. He will be doing damage that will come back to him!
Hang in there, be the better person, no negative comments about Daddy, don't react to their behaviour and try to put the ball into their court, make things the children's decision. Try comments like "I love you very much and understand that you are hurting, let me know when you would like to talk". Also, things like "it must be difficult for you at the moment let me know if theres anything I can do to help you".
Children do eventually process information and gain an understanding of what is actually going on, they shouldn't be involved at all, just have two loving parents in two different houses. If only!
I hope I have helped you please click accept if I have, please message me if I can help you further.