The 36 hrs a day book suggested not going one on one. And I think it works. My wife will ask "When is Mom coming home?" and I would say "She died years ago" and that would upset her. Now I say "I'm not sure. Lets wait and see" I felt bad at 1st but after 2 minutes it is all forgotten! Might try something like "Oh, alright dear. Let's watch some TV (have supper, have some tea etc) and talk about it later."