I'm am so sorry for your loss - Milo was a beautiful little guy. I do believe animals grieve, so I second the suggestion to sit down with Nora and just tell her what happens....she'll probably understand more from your tone of voice and body position than your words, but I think she'll understand something. And, I think getting her, and your home, a new kitten will probably be a good idea. Will never be another Milo, but may help to fill up some of the void you're all feeling.