Terry,
I'm sorry I missed this - I know the feeling of needing to "get out" of an ugly situation.
Like the others, I agree that there are no winners here. If your difficult child is like either of mine, he will feel that he has a great deal of power. However, at what cost?
Saying that, you & husband are a separate issue. If husband is so stuck on not contributing or backing you up he needs to stay out of the fray, so to speak. When my husband didn't contribute I let him know to either put up, shut up or get out of my way.
husband has since learned (when he got little to no respect from either of the tweedles) to contribute to family life including the ugly stuff. He stepped up to the plate ~ until then life around here was iffy. And that was our problem, not kt or wm's.
I hope that life in your home settles down for you. by the way, the more I detached the more my husband stepped in; in a positive manner. When I started golfing more & leaving whichever tweedle home with husband he had to deal with it. I took up piano then art & stepped back even more from the incessant demands on a daily basis.
Finding daily therapeutic outlets for myself helped me sort out the issues I had with husband; helped me realize that it takes two to make or break a marriage. During our therapy I learned to back down a great deal & really listen to what my husband had to say. I began to see that not everything he was saying or doing was "wrong"; it just wouldn't be my choice. We have since learned to sit down weekly & work out any issues that have come up, discuss our options & make a decision together. If one or the other of us decides not to deal & the other has to take an issue on, the "slug" has to shut up. It has really worked for us.
Good luck in whatever happens.