Seriously OP, I know you don’t want to live there, but I would consider buying him out anyway. That’s a large house, so, I would buy him out and then rent it out for a period to a family.
Then, use the rental income towards your own living costs, be that rent or a mortgage on another house.
You need to push this forward and while he is living there nothing is going to move on.
Once the house is in your possession, you have complete control over what happens to it.
At the moment, he has the control and he is obviously revelling in it. I would not give him the satisfaction.
Consider also, if you are forced to drop the price by say £30,000 (because he’s being an arsehole) also if a new EA was appointed, I’m not sure what the selling fees are in UK but let’s guess £4,000
Your are then left with £166,000 split 70/30 = £116,200 / £49,800 (less any outstanding mortgage amount)
If you buy him out, you may possibly get him to agree on £10,000 below current asking price.
that is £190,000 split 70/30 = £133,000 / £57,000 (less outstanding mortgage)
Or wait till he agrees to drop the price by £30,000 then make your move and save even more.
Im not an accountant so the above could be seriously flawed, but on the surface it looks like you would both be better off.
Just try thinking outside the box, he might be a bully, but he’s not a very clever one.
Good luck OP, I take my hat off to you, escaping with six children and starting from scratch shows what a strong woman you are. Use your strength and turn this around, in your favour.
PS get proper financial advice first in case I’m talking bollocks (-: