Hi Psych, I've seen your postings here as of late. I would have responded earlier and would post more, but I cannot give more than the support of this one post, at this time.
I feel I understand you and your sitch well enough to say that I believe you have tried your best to make this work and your M survive.
Having said that, perhaps it is time to stand still, regarding changing yourself to save the M.
I know that when one is so enmeshed in something and working on it, very hard, for a long time, burnout occurs. When that happens, the only thing that helps is to take a break from it. Rather than working harder and trying to push on. That is the purpose for vacations and sabbaticals. Perhaps... that is what you need.
Perhaps truly working on GAL, focusing on your kids, and planning on a future that may not include your W, is a place to put your full attention.
Give that some thought. You have poked and prodded and tried to fix your M. Trust that God will show you the way to a better future, regardless of what that future may look. And that you go willingly, in growth, towards that future.