I am so sorry to hear of your loss of Snowflake.
hno: I can tell she was very loved by the way you speak of her and your concern about her grieving mate, Sky. It sounds like she had a great life in your home.
I would try to keep Sky's routine as similar to what he is accustomed to, and of course follow the other great pieces of advice already given. I also like to play soothing music (nature sounds, ocean sounds, etc.) all the time, but especially during difficult times. Fly free, Snowflake.