You are coming in for a lot of flak here OP.
He is an adult. Supposed to be a partner. He cannot blame you for everything. You say he has an important job - He clearly has the ability to speak up. There are two of you in this. Not one. Therefore the "blame" if such it is, is shared.
He wanted a fab house, all done up for him he just didn't want to deal with any difficult decisions or face reality.
What strikes me is when you mentioned that he would agree to something.. Then say no, then agree again.
From my own experience, it is dreadful dealing with someone who does that when you re in the middle of a project...
You can't just stop and start renovations once they've started.. or you'd be left with half a roof.
Nor did he sit down with you and try to work out what could be done to prioritise, cut or defer expenses, how you could save money by doing it yourselves.
Now he's left you with a half done up unaffordable house in what sounds like negative equity and its apparently your job to deal with it all. He won't get involved. Such a childish attitude.
You may have made mistakes (having never done up a house before) but his attitude is pathetic... "someone else sort out my mess for me. Its all her fault."
It also sounds like he sold shares when the market tanked and now rues the day as the market recovered... He should have got better advice and found some way to delay the sale. Only he could have decided to use his ISA and shares to fund the renovations.
I would get two estate agents quotes of what the house is worth now.. and decide what you want to do.
Get some indepdendent advice on how you can reduce the loss.
Do you want to stay on.. continue doing it up bit by bit. As people have suggested, get a lodger? We've taken years to do up our house. There's always more to do, but it is an asset.
but try to work out the immediate priorities and costs for that..What can be done yourself? There are loads of videos onYou Tube to help.. which were'nt available to my generation.
Or do you want to sell up and downsize.
Do you want to stay married or split.
It's very difficult for you when he's not around to discuss this with. But you need to get some support and maybe see a councillor yourself to talk these things through.