My ex-husband is declaring Chapter 13 bankruptcy. He is listing a joint credit card we are both paying off. Will I now have to repay all?

The bankruptcy of your ex-husband will not relieve him of any obligation in the divorce to make any payments, but the creditor was not a party to your divorce, and has the right to go after you.  The chapter 13, however, will result in a stay of the creditor's actions that applies to both you and the debtor, as this is a consumer debt.   The creditor can get relief from stay, but would have to go to court.  You should check his plan and see what ir provides.