Because no matter whether you apply for a municipal provident fund loan or a state-managed provident fund loan, you need to satisfy the borrower (married couple) that there are no outstanding housing provident fund loans and housing provident fund policy discount loans; The provident fund account must be opened and continuously deposited for more than 12 months; Provident fund is still among these three conditions. But you and your ex-husband didn't pay off the loan for buying a house with the provident fund.
So if you want to pay off the provident fund loan, you can use the provident fund loan to buy a house.
Source: /index.jsp (Housing Fund Management Center of Central State Organs) and/(Beijing Housing Provident Fund Network).