it's sad to loose a fur-face... especially one you have put so much time into caring for. And with Tartar-Sauce (aka, Grumpy-cat) who suffered from birth defects, I'm sure her cat-parents had to spend a lot of hands-on time caring for her. But modern kill-the-animal-at-the-first-sign-of-illness veterinary medicine is worse than modern human medicine. Your cat has a urinary track infection? euthanize it.
Still, she had 7 years of love where just a few decades ago she would have been put down
shortly after birth. bless her hoomans.