I'm sorry for your loss of stuie. the fact that he was an outdoor cat part of the time and lived to be 21 says alot for how well you cared for him and loved him! it sounds like that kitty door sure made him happy! you know he loved you and is watching over you now.these next couple weeks will be the hardest. soon all the memories will make you happy, not sad. open up the photo albums and hang pictures of him on the wall, when you are ready.