I married a widow who had a farm and was losing it. I was asked to sign a paper stating that I, nor any of my family would lay claim to the property. I was told that if I did not sign this paper, I would be held responsible for my 'new' wife's debts. Is this true!

Welcome to AMHD, and condolences for your loss. Responsible for your wife's debts? No. How were you "told"? 'They' could have been telling you that the farm is going to be sold unless you make arrangements to pay any debt for which it is pledged. Do not be coerced; get legal advice.