There comes a time in every dog's life, where their suffering is constant and far worse, and a peaceful dying, is a release from their horrible existance.
Yes, I've put family dogs down three times, and yes, you come out of the vets howling with your poor dog in your arms, but.....
1. you were with them all through the gentle process
2. you spoke to them as the needle went in
3. you see it is over
very quick
4. you
know they are not suffering anymore.
I'd say for about a week you just want to comit suicide yourself to be with them, but other things keep you going, and another puppy is always something else to focus on......
......
BUT YOU NEVER FORGET THEM ! 
Doing it in the first place is the hardest and most difficult decision, as you never think the time is right, but on reflection, and I and all my friends have agreed with this, you realise that you left it too long, and not for the dog's sake, but for yours. You especially think that when looking at last pictures of your dog, and see how miserable they really were - with pain etched all over them which mostly you were blind to.
DO WHATEVER IN YOUR HEART YOU KNOW IS THE BEST FOR YOUR DOG.
GOOD LUCK, WILL BE THINKING OF YOU, AND YOU KNOW TO COME HERE TO TALK IF YOU DECIDE TO GO AHEAD
Debra x x x x