Sorry to hear that. It's tough to go through. My kitty, Sassy, had CRF. It was VERY advanced when I took her to the vets. The vet told me, in a very straightforward, uncompassionate tone "She's in renal failure and she probably has lymphoma." She didn't have lymphoma, fortunately. The vet gave me the option of having her stay there to "see if she makes it through the weekend" or euthanize her. I choose to keep her at the vets. I visited her every day and called several times a day to check on her. When she came home she had SubQ fluids every night along with a Pepcid pill to help her stomach and k/d canned food. She wouldn't eat on her own so I syrringe fed her a mix of the canned food and baby food. I did this for 3 weeks until she died in my arms. It was so horrible watching her like that. Oh, and on top of that I got an 11 month old puppy 3 days before she was diagnosed.
I am so glad you caught Tigger's early and he's doing well. I really hope you get many more years with him. There is a really great yahoo group for CRF cats that helped out a lot when Sassy got sick. And they referred me to a group for syrringe feeding her when she wouldn't eat.