If the mortgage company is foreclosing on my home but the mortgage is in my ex-husband's name only, can I file bankruptcy on his mortgage loan?

if you want to save the home from foreclosure and pay the mortgage, and/or cure the mortgage, you can do that in a chapter 13 bankruptcy.  if you do not want the house , tyhen you will not owe the mortgage company any money after foreclosure- they will go after ex-h.  if you were ordered to pay the mortgage in the divorce, then your ex-H can come after you for whatever he has to pay on that mortgage debt.