No.
An AU is not legally responsible for repaying the debt to the creditor as it is presumed that the AU has no control over the account itself.
Hopefully the AU would consider it their...
depending on who was using the card, that's who's fault it would be...I'm going to assume since it was your spouse's credit card, that your spouse is then responsible for it.
Generally, the person that signed up for the credit card is responsible. If any users were added to the account, they are also responsible. This include joint accounts. You cannot inherit credit card...