Refinance vs foreclosure of ex's house

[annihill1016]

My ex-husband's wife called me today and said that someone has contacted them and said that he would be able to help my ex refinance his home with a lower interest rate than what he is currently paying (6.65% is what he has now and his payments are over $700/month). He has had trouble making the payments, but is determined that he wants to keep the house. He is constantly late but thinks that he would be able to make these lower payments and keep them current. The only catch is that because I am on the mortgage, I would have to sign the refinance papers with him. My ex said that if I didn't sign the refinance with him he would have to file for bankruptcy. I currently live with my husband and children in my father-in-laws home rent free. I am planning on buying a home in the next year or two. My current husband has a bankruptcy and home foreclosure on his credit from his divorce in 2004. What would be the best thing to do in this situation? Should I let me ex file bankruptcy so that he can could keep this home as his primary residency or should I sign the refinance with him? What will this do to my credit and how will it reflect on me when I do go to buy my own home?