Andy that is a very sad ending to a lovely happy story. You have to console yourself with the knowledge that while the cat was not able to tell you herself she obviously felt for you enough to stay with you, and that to me tells me she had a very happy life with you.
My cat, Callie was a rescue cat I got her when she was about 6 years old and that was about 3 years ago now. I am dreading the inevitable but I keep telling myself if she was not happy then she would have left by now.
Pets are just like family and that is why I get upset at the mistreatment of all animals, and the main reason I am a vegan.