I'm so sorry about your kitty--I'm sure this must be an awful time for you. I once read a quote that I unfortunately can't find, but the idea behind it was that pet owners make the ultimate sacrifice in loving their pets, because they know that they will probably outlive their pets. But, of course, you are the better for having had your kitty in your life, and she was the better for having you.
I hope you can take some solace in being able to hold her until the very end--what a wonderful gift to give to her.