*hugs* It’s tough, it sucks, but just use the time you have left with her and spoil her silly. 😀
I’ve been on the ends where you know months in advance, and when you don’t know until the week or so before, and some people say one is better then the other, but they both suck. Just for different reasons. Hang in there, ok? You at least gave her a loving home, and she obviously showed you her appreciation, by being a loving, affectionate cat.
If you don’t mind me asking (or don’t mind talking about it) how did you get Katie? Was she a rescue, sold at a pet store… etc?