arborman, I'm so sorry to hear what you're going through. I've been to the bottom of that pit a few times in my life, and it's never easy climbing back out.
I've also recently experienced a bit of what you're describing from the other side. Last year, Mr. Sun's job went from ok to horrible, as the project he was working on was shut down and he was transferred into what is lovingly known in sofware circles as a "Death March". In fact, he was promoted to some sort of authority, which at first seemed good, until he saw what was going on. The long days. The sleepless nights. The coming home from work and collapsing on the couch for an hour from sheer mental and emotional and spiritual exhaustion. The declining health. The lack of joy in life. It was not good.
He felt he had to keep going, seeing as he was making 1.5 times what I do and we knew we were (hopefully) going to have a child. But, after watching him suffer for longer than I should have, we had one of 'those' talks. What he was doing was not good for him, or for us, or for the child we were going to raise. So, we talked with the financial people, tightened the budget, renegotiated the mortgage, I started working overtime when I could, and he left. It was a shock to the pocketbook, but the difference in him was worth every penny and twice again as much. I had my partner back.
He's still at home, working solo, and slowly recovering from other health problems. Occasionally he grumbles about having to return to the industry, but there are many other options. We've talked about having one of us (and it's looking like him now, unless his company really takes off, which it might) stay home for the first few years. There are lots of city and community centre provided play groups that provide the socialization aspect of day-care at no or minimal cost.
I don't want to assume too much about your situation, or say that it will be easy or obvious how to make it work. It is hard, and it involves challenging how we value our contributions. But it is undeniably worth it. Sometimes, the best support you can provide is not financial, but to be a healthy and happy partner and father.
And know that all of us are here for you and wishing you the best.
Take care, arborman.