I'm glad you and the family are safe, even though not having power stinks.
As for your cat -- it's natural to want to protect yourself from grief. I've gone through the same thing with chronically ill pets, and each time is exquisitely, painfully unique. I'm not going to tell you that it will all be better. Just allow yourself some time to be sad. Don't try to cover it all with cheer and convince yourself that you're a bad person if you are angry or sad. If you let yourself go a bit, you may find it's easier to enjoy her company for its own sake.
Thank you so much for the words of comfort and sympathy. They mean a lot.