Maybe this is corny but it makes me feel better:

Dearest Miaka aka Buddy,

Thank you for being in our lives. You made my relationship with Manny stronger. The minute we got you, we definitely fought a lot less. I will always appreciate the times you stayed in bed with him while he was recovering from surgery. You were a source of comfort to him and you made it easier for me to be at work and not worry so much. We've been through a lot together and you were a real trooper on your first plane ride and and the crazy move we made to LA.  Thank you for making us laugh with your weird cat behavior, for being so sweet and cuddly and for being a friend/roommate to Jelly. I know you are in animal heaven playing with the other animals and eating all the delicious food you want.

Love,
Meg