Saying Goodbye to Darby

I am so sad. I am sitting here at ten minutes until 8 in the morning waiting for the vet's office to open so that I can call and tell them that I think the time has come to put Darby out of her misery. My poor, sweet kitty is just too ill. It has been hard for me to come to terms with it, but I just can't ignore the signs anymore. Yesterday she didn't even get off the couch -- not to eat, not to use the litter box, nothing. She can barely move. I don't want her in pain or discomfort. After 15 years together, it's time for us to say goodbye. I don't know how I am going to do it.