You could talk to your mortgage provider. Explain that you expect him to stop paying the mortgage, knowing you can't afford to pay while also blocking the sale to be vindictive during an unpleasant break up. Ask for their advice on pushing him to pay or sell. They have special teams for this kind of thing.
Does your mortgage allow you to rent the house out? Maybe the mortgage provider would allow you to convert to that kind of mortgage. You rent elsewhere, tenants cover the mortgage.
I'd talk to estate agents asap about getting the house on the market as soon as he starts playing silly buggers. Tell them the situation too.
If worst comes to worst, don't pay the mortgage and risk repossession. He'll blink first.