As Greg so aptly stated, Timmy cannot be replaced. There can only be one first. His replacement (if wife still wants to breed them, we need a new stud) will never be Timmy. He'll be just as big a nuisance, annoyance, pia, look like, act like, but won't BE Timmy.
The really amazing thing is that I had become attached to him. I thought I had immunized myself to prevent such an occurance. While I've never had to put a pet to sleep, I have "lost" many pets, some disappeared (indoor/outdoor cats), some died, and one was "lost" due to divorce. Putting Timmy down was the hardest.
I know it was the best/right/only thing to do. Sometimes rational and emotional do not equate.
He's a sad memory today.
And thanks, you've been a big help with my coping.