Peter I'd also like to say that I understand your grief and feelings of loss, and hope that the pain lessens swiftly, leaving you only with the good memories of lives spent together.
I won't go into details here, but just last Monday week I too had to have one of my 2 best friends in the world put to sleep. I knew for 5 weeks that that day was coming, and I dedicated myself to making her final days as pleasant and happy and comfortable as possible. Even when the time came, and I knew she would suffer if I selfishly kept her with me, it was the hardest thing I have ever had to do, and I cried like a baby. I grieve still, and I'm not too big or too proud to admit that I still cry each day.
I feel for you, and for your family, and I truly hope you find peace in the memories of good times that you will carry with you always.
The "Pet's Prayer" as it's known (posted by scarper above) was something that I'd found on the net prior to having to do what had to be done, and it helped me through, as did the following piece. I hope it warms your heart too:
Just this side of heaven is a place called Rainbow Bridge.
When an animal dies that has been especially close to someone here, that pet goes to Rainbow Bridge.
There are meadows and hills for all of our special friends, so they can run and play together.
There is plenty of good food, and fresh water, and warm sunshine, and our friends are all happy and comfortable.
All the animals who had been ill and old are restored to health and vigor; those who were hurt or maimed are made whole and strong again, just as we remember them in our dreams of days and times gone by.
The animals are happy and content, except for one small thing; they each miss someone very special to them, the person that they had to leave behind.
The animals all run and play together day after day after day, but eventually a day comes when your pet suddenly stops and looks into the distance. Their bright eyes are intent; Their eager body quivers. Suddenly they begin to run from the group, flying over the green grass, their legs carrying him faster and faster.
You have been spotted, and when you and your special friend finally meet, you cling together in joyous reunion, never to be parted again. The happy kisses rain upon your face; your hands again caress the beloved head, and you look once more into the trusting eyes of your pet, so long gone from your life but never absent from your heart.
Then you cross Rainbow Bridge together....
Author unknown...