Oh John, I am so so sorry you've lost little Sable. I know how much she means to you, how incredibly precious she was to you both.
It was the hardest thing I'd ever had to do in my life too. Making that decision tears you apart even when there is absolutely no way around it. It would've been too frightening for her to try and carry on another day... she is in peace now.
I know the awful stillness where paws should be tapping across the floor. Keep telling yourself that she knew how much she was loved, every single day of her life.
with love and my deepest sympathy for you both,
mig