Oh sweetie. I'm so sorry. I was hoping things had run their course and he was working toward rebuilding his relationships with his family. ARGH. You know the drill-- If it's not working......
I know your goal was to save your marriage. In the end though, what matters, is saving ourselves, and hopefully the marriage can become better than the one that brought us here. I hate seeing you hurting like this (But so very glad you are posting!).
You can't work on a marriage with 3 people in it and from what you write, I'm afraid you should listen to your instincts and protect your heart. Gas-Lighting is just cruel and you have too much self respect to put up with this indefintely.
It's spring. Maybe it's time to take another look at those goals? If you think he has an exit date/plan, maybe we can brainstorm some ideas to put a wrench in his plan?
Can we start over and figure out some ways to shake this thing up? Can you start with small home improvement projects that'll be more for him to lose (a 180?)? Plan some trips for Son's summer vacation whether H can go with you or not?
As JAK says above re: the cake eating--IF he is continuing the A, what would motivate him to end it if things just stay the same???
I just need to think about this a while and hopefully others can come up with some ideas in the meantime. Your S is seeing all of this and that can't be good...