I had a cat, Naomi, who lived to be a little over 18 years old. She had kidney failure as well. I gave her fluids for six months but one day she couldn't walk anymore and that was it. It gets easier with time. Remember the good things. Yesterday, I had to put my cat Prudence to sleep who was only 5 years old. I wrote about her in another thread. Cats are so wonderful, but most of the time we outlive them.