Wow. You have quite a complex group of issues going on. Do you feel like your husband is manipulating you, either consciously or subconsciously? When you are going through what is quite evidently, (even to me, and I'm a stranger!), as extremely difficult, challenging times,...the last thing that would be productive is issuing you ultimatums and threats.
Your entire post was extremely logical, well thought out, pragmatic, and in my opinion, dead-on right. Your analysis of breaking down the situations is very well stated.
It sounds as if your husband, and perhaps your family (?) is placing quite a burden on your shoulders, expecting you to do all the work. Things like "fixing a relationship" when there's 2 people in it, is not the responsibility of just one person. It takes two to make any relationship functional.
Have you expressed to your husband how his ultimatums only distance you, putting that victory of success so far out of reach?
It sounds to me, (and I'm just a little observer over here), that he's using your marriage and your health as pawns in a chess game. If it isn't your father, then it's your health. If it isn't your health, it's your mental stability. As you eloquently put it, with all of these things piled up on your dish, I am getting exhausted just reading about this!
M.