Preparing to say good-bye

How does a person really prepare to say good-bye to a loyal friend?  Someone who has loved you and you have loved back unconditionally?  That is the challenge we face in our household as we prepare to say good-bye to Sophie. She was recently diagnosed with chronic kidney injury (what used to be called chronic renal failure).  In other words, her kidneys are failing her.  There are no known causes, prevention or real treatment options.  Her days are limited.  The only saving grace is that her vet says she isn't likely in pain, but she doesn't feel good. She has rejected eating dog food, so I have begun to cook for her, but she's begun to get a bit finicky about that too. I am thankful for each day she's still with us, but I'm completely heartbroken over the fact she is dying. I'm not ready to say good-bye, but I know the day will come in the not too distant future that I will have too. I am so very, very sad.