Home depot, and probably gas too, is not considered a family necessity. If the charges were for mixed things, with food being one of them but not the majority, then most likely you would never be held responsible for it.
If MOST of the charges were for life-and-death necessities (food, shelter, medicine), then if the creditor were to sue, they could try to argue you are responsible....I forget the term, DC help me out? It's not a certainty by any means.
But that would only ever come up in a lawsuit and would be decided by the court. And more then likely, it will never come to that. If your husband defaults, they will pursue him, and if they try to go after you, you can safely tell them that you are not a joint account holder and buzz off. If he should die before you, his estate will be responsible for the debt, but YOU are not.