You are not liable for your deceased husband’s credit card debts especially because, as you mentioned, he did not leave any property that could pay for the debt. In addition to that, if he acquired the debt during the separation while the dissolution was in progress, you are not liable for that even if he were still alive; except if you or the family benefited from it. It is better to personally consult a lawyer who handles debt cases for advice on how to properly respond to the summons and other possible demands from your husband’s creditors.