No, they don't actually have nine lives. I had to put my last cat down, too. It sucked... He was, also, my best friend. Fortunately, just some few months ago I came into possession of a new cat. He's a lovely cat, and I swear he's my old cat's reincarnation.
So, what I'm trying to say is, just love your cat until she dies. It's really all you can give her. And later on down the road, go look for a new cat. I'm sure you'll find a new cat that you'll click with and enjoy.
It's going to be so hard.. We were so close... I understand what you are saying though. If she does die I'm going to get a cross made with her ashes in it.