So sorry for your loss and the decision you are being forced to make, as an animal lover and one that will take in anything on 4 legs, I feel so deeply for you right now. It isn't easy, and as much as we'd like to think they will live beside us forever, they just can't do it.
We had to put down one of my mini horses last Monday and it was one of the hardest things I've ever had to do... so I feel for you. She had a neurotic disease when we got her and I knew this, but we had 3 years with her, which is 2 1/2 more than anyone said we'd have her. She passed happy and had as much of a good life as we could give her.
Just do what we have to do to get thru this, keep a good thought and know that you are doing the best thing for him... he had a good life with you and you have made such a dear friend with so many memories.
