The other option would be for your ex to perhaps propose a full and final IVA .
In this instance she would offer a lump sum to the creditors in full and final settlement, however she would need to talk with or seek advice from a practitioner, she could settle for as little as 40p in the £1.
As you point out she will have a £15,000 shortfall if the house is sold and would walk away with nothing in Bankruptcy so this could be the best alternative for you both.
It would be dependant upon the credits voting in favor of the settlement though.