There are several alternatives.
1.If you are confident of a forgery, make a complaint to the Bank in writing and send the same by Registered post and seek for inquiry. Now, any one can compare signatures and can find out the forgery with use of magnifier app available with every computer.
2.Also send another registered post to Bank stating that you are willing to pay the entire loan subject to the bank handing title documents, but this may not help the cause as the property is joint names.
3.You can file Pre Litigation conceliation before District Legal Services Authority against your spouse and bank also and can record your attempts.
4.The Bank must as statutory obligation must provide statement of loan account to any borrower / joint borrower and one can issue a simple notice under CP Act demanding such statement of account.
The above suggestions are not remedies but only cost effective relief to record your sincerity in repaying your part of share. The bank is always safe as they can auction it and get entire amount due to escalation in real estate prices and they can even charge penal rate and more costs. Litigation should be the last and ultimate remedy, if conciliation fails.