My condolences, Royale.
In my case, I had to put mine down a few months ago after 14 years. I set up the appt on a Monday, had the procedure done on a Friday. It was the hardest phone call to make, and the worst week of my life.
I think the key is putting your dog first. It's not about you, it's putting your dog out of its misery (if they are indeed in pain as indicated by their actions and movements).