My old man Fidget, my ferret of almost 8 years, has to be put down Monday...

He went to the vet back in July for a swollen tummy, to find out he has an enlarged spleen (which means his body is storing blood, in anticipation of being very sick), his liver has lesions (which is one of the major precursors of cancer, and also explains the spleen enlargement), and possible kidney failure in the works.
They told me at his age (being roughly 2 years older than most ferrets ever make it), that there really wasnt anything they could do for him that wouldnt just be painful, and exausting for him, and more than likely not very successful. I was just supposed to keep an eye on him, and if it got bad, bring him in.
Well... two weeks ago I noticed he was stumbling a bit more than his usual clumsyness, and he's been sleeping more, and drinking LOTS of water. The other evening, I was laying in bed, and heard a lot of scratching, looked over to see him struggling to get to his water bottle on the 2nd floor of his cage. He couldnt get up the ramp. He was using his front legs to pull himself, and didnt have the strength in his back legs to push.
The vet warned me that with his tummy swelling, his back legs could become unresponsive...
So, I called them first thing the next morning. They told me that they could prescribe pain pills, but I just couldnt see the point of just medicating him for the sake of keeping him around to suffer... so I made the appointment.
It was probably by far the hardest thing I've ever done... and I havent even actually done it yet...
His appointment is at 5:30pm Monday... And I can't stop crying... I look at him, I think about something at work, it doesnt matter... I feel so awful. I dont really feel guilty, just so damn depressed. I dont like having a countdown... I dont like knowing that I have 3 more days with him, and at the end of the 4th, I end his life. But I REALLY dont want him to suffer, at ALL. I love him entirely too much to even comprehend the idea of trying to put him thru chemo, or medications. I will miss him, sooooooo much... I cant even express, but I dont want him to hurt... I dont want him to struggle... But God I wish I could stop crying...