We went through similar a few years ago.
In some ways I think it was easier for me in that it all happened fairly gradually.
First dh was periodically off sick a day here and there and wasn't paid for these, and I worried about money.
Then he was off longer term and only got stat sick pay, and I worried about money.
Then his sick pay ran out - more worry.
Then he was sacked but got (at the time) contributory jobseekers, so ironically we were better off than we'd been in a while.
Then that ran out and I had to get a second job and dh was a SAHD for a few years and then retrained.
At the beginning of the process I would have said there was no way we could have afforded him to retrain even though he was bloody miserable so I guess that was a lesson on what is actually manageable - life is so much better now in every way.
I had a LOT of feelings, and like you didn't always have space to deal with dh's emotions as well. I got through it by being ruthlessly practical, which I guess gave him the space not to worry about those things so much, but I did feel a lot of resentment at times which I kept to myself.
I would spend the money op, but your dh needs to show some willing too in considering any financial contributions he can make, whether that be selling things he doesn't need, budgeting, even doing tiny things like paid for surveys or considering gig economy jobs for a bit.
It will get better though - this shocking bit when it's all new is often the worst.