Very sorry to hear that. 



Amy, I'm sorry to here about your cat. I was dealing with the same thing for a couple years before I had to put my Max down last April. I had been told two years earlier that he was starting to go thru renal failure (early stages) and they were never sure how long he would last.
In discussing treatments, I was advised about the saline solutions to be injected, but I couldn't do it. Max was 17 at the time, and I didn't have the heart to poke him with that needle on a regular basis. At his advanced age, I gave him whatever he wanted. I'd share my french fries with him, tuna fish, etc. Every night he slept next to my pillow at the head of the bed. He was the best pet I've ever had and he's greatly missed.
Like you, I had to put him down on short notice. He got to the point where he couldn't make it to the litter box and peed all over himself while I was out. He wasn't happy with that and after giving him a sponge bath and a toweling off, I had to make the same call. I cryed like a little baby. Even after two years of knowing the day will come, it doesn't make it any easier. I'm glad you enjoyed the time you had with your cat. Pets are always a wonderful moral boost when we get home from work, along with day to day interactions, it can truely be devestating when they have to be put down. I'm sorry for your loss!
RIP Dumass!