I think its a test question for all males and in essence their is no right answer.
Course in your case, you took it much deeper and deserve her reaction.
At one level, ones wife is concerned about you if something happened to her and thus the question .
My half sometimes picks out someone for me and says if something happens to me you should marry her ! I've learned not to respond in a positive way.
If I say I'll just keep the house and furniture when I re-marry then I hear something about being haunted at night , course best is my son-in-law telling me him and my daughters have to vet the new lady first and chat with her.