Rick, having to put a dog to sleep is a terrible thing to go through. It sounds like he was your partner for a long time. It is a thankless job to have to make the decision to put them to sleep, but I believe it is the right thing to do when they are in pain and/or suffering.
They give us everything they have and only ask for some clean water, food, and a warm spot to sleep. I have two four legged friends in the house, and I dread the day that I have to part with either of them.