Believe me, I know how it hurts. We had to put down one of our Shelties due to liver failure on December 26, 1999. Sandy (my wife) had watched Beau's litter grow up from the day they were born at one of her friend's house, and she picked him out as her dog within a few days (the runt of the litter). Unfortunately for her, Beau latched onto me when he came home, and he was a best friend for 13 years and 10 months. He's buried out behind our garage.
Did it hurt to lose him? My eyes are tearing up right now as I'm typing this. We got another Sheltie within a few days, and Bandit (a tri-color male) is a neat dog, but he can't take Beau's place.
Here's something that helps me deal with situations like this that involve our pets:
Job 12:
7 But ask now the beasts, and they shall teach thee; and the fowls of the air, and they shall tell thee:
8 Or speak to the earth, and it shall teach thee: and the fishes of the sea shall declare unto thee.
9 Who knoweth not in all these that the hand of the LORD hath wrought this?
10 In whose hand is the soul of every living thing, and the breath of all mankind.
Rusty