Transfer of equity & debts

mogsy12

Hi I'm not sure if this is the right place but I would like to know if there is any sort of legal document myself and my ex can sign.
We split up nearly 2 years and have tried to sell our house knowing that once we'd paid off the mortgage and our credit card debts we would still come out of the sale with £5K debt each. These credit card debts apart from one were all in my name although they were for joint purchase and living costs and we both paid half each (minimum payments only so no chance of reducing them either!). Although he had moved out he still continued to pay half the mortgage and half the card bills until he had an accident just before Xmas and hasn't paid any since.
Luckily I've met someone else and he has pad off these credit card debts & a lump sum off the mortgage and we are in the process of remortgaging to get my husband's name off the mortgage and my new partner's name on it. As part of the process of transfer of equity we have had to pay an insurance policy to cover the lender in case my ex goes bankrupt as the transfer is considered under value and no actual cash has been given to my husband but the debts have been paid off.
He is still unable to work and is behind on his own loans/credit payments so there is a chance he could go bankrupt.
Basically is there something that could be drawn up to protect me and my new partner as the insurance policy is just to cover the lender not us.
Sorry for the lengthy essay but I wanted to include as much as info as possible!
Thanks in advance for any advice.