probably should post in family law...
But.
You need consent orders. Basically, a legally binding agreement that stipulates how assets are to be divided. Nothing is simple. Lets pretend the house is worth $500 000. You owe $300 000. So there is $200 000 equity in the house. You would likely have to give him $100 000. So you need to be able to refinance and buy him out. You're also gonna have to pay half the stamp duty.