T, Your wife is thinking out loud. She still has a lot insecurities about the way she looks and her life as it is right now. I would respond with something like this: "W, I read your email and I want to thank you for sharing your feelings with me this morning. I do understand some of what you are feeling right now about the boys and the house being empty. Would you like to sit down this evening and discuss what you are feeling with me?" Put the ball back into her court and see if she will respond back to you w/a yes.
Your wife is reaching out a bit w/these snippets.
Good luck!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.