I am sorry for your loss. I understand how you feel, I had to put my baby down a little over a month ago. He was only 4 though, and much too young to go. Here is a quote and a poem that really make me tear up, but also to understand sometimes it really is the best thing to do.
To place your horse's need for you to let him leave his failing body above your need to keep him with you - that - is the greatest and purest love.
You're giving me a special gift,
So sorrowfully endowed,
And through these last few cherished days,
Your courage makes me proud.
But really, love is knowing
When your best friend is in pain.
And undertaking earthly acts
Will only be in vain.
So looking deep into your eyes,
Beyond, into your soul,
I see in you the magic, that will
Once more make me whole.
The strength that you possess,
Is why I look to you today.
To do this thing that must be done,
For it's the only way.
That strength is why I've followed you,
And chose you as my friend,
And why I've loved you all these years...
My partner 'til the end.
Please, understand just what this gift,
You're giving means to me.
It gives me back the strength I've lost,
And all my dignity.
You take a stand on my behalf,
For that is what friends do.
And know that what you do is right,
For I believe it too.
And don't despair my passing,
For I won't be far away,
Forever here, within your heart,
And memory I'll stay.
I'll be there watching over you,
Your ever-faithful friend,
And in your memories I'll run...
A young colt once again.
Never approach a bull from the front, a horse from the rear or a fool from any direction.