I have a question about marital debt in a divorce.

I''m in the beginning stages of a divorce. We we''re married in Oct. 2001. In March of 2001 my soon-to-be husband borrowed money from his father to cover living expenses after he was laid off. He signed a hand written promissory note to pay his father back with 6% interest. The borrowing continued on and off until 2005. We always had separate bank accounts so I was unaware of the extent of the borrowing. My husband has not paid anything back to his father. Now, my husband is trying to gain possession of our house stating that I owe his father $88,000 (half of the loan) that has accrued 6% interest since 2001. My question is, am I responsible for this debt? Thank you for your time!