How can I make Ex sign QCD?

My Ex and I have been divorced for 12 years. We bought a home together 5 years ago, during a period that we were working on getting back together. This didn't work. We invested $50,000 on the purchase. I've paid for taxes, insurance and maintenance on the home since it was purchased. Ex did not contribute. I moved into the home 2 years ago. Now, I'm behind payments and working to modify loan. Ex refuses to sign a QCD and bank won't modify without it. I've offered to pay him 1/2 of the investment ($25k) and he won't accept. Eventhough, the home isn't worth what we paid for it and his share is actually less. Is there anything I can do to dissolve our partnership (force him to sign QCD) and I don't lose my home? He's on the loan and deed.