I'm in the same situation with my chn - about the same age as yours. I'm trying to strike a balance - not defending AH but nit supporting him either.
I tend to say that he loves them very much, and I don't understand why he needs so much time on his own. I tell them they are both soooo important to me, I love them more than anything, and they will always have me. I don't see the point in putting AH down - I need them to see how I am separating out him and his behaviours, without really telling them how angry I am.
I dont know if I am doing it the best way. It is very hard.
Just keep aiming to be the best Mom you can be, and be waiting in the wings as they figure it all out. That's all we can do.
I've offered them counseling, but they also have the phone numbers of some close family who they respect who they can talk to if they need someone other than their mom!