I just last week put down GF's daughter's dog who has lived with me for 3 years. That was tough, but not as tough as the rescue dog I had for just 4 years.
I have 2 more, both will be 8 this year, and the Olde English Sheepdog has health issue. But you know what, I would not miss their company for all the tea in China, even knowing what must eventually come. I still remember the rescue dog, Crash by name, Black Lab/Dalmatian mix, seeing bunnies for the first time in Wyoming. She buggered a nest of half a dozen or so, and I almost fell off the ranch house porch laughing as she spun in circles trying to figure out which one to chase.
Remember the good times, Bill, cherish them. It will help . . . a little.