I am getting married for the second time in October. However, in the divorce settlement of my first marriage, my ex agreed to pay the student loan we

The divorce decree does not affect the status of any loans.  If you fail to pay or your x fails to pay a loan that they signed for, the lender will seek recovery from whoever signed for the loan.  The only recourse is to file a Motion for Enforcement in court, but if they do not have the resources to pay, then you will not recover the money anyway.