I'm very sorry to hear about your dog. I had to put my dog down in January and it was very hard, but I can honestly now a few months later it does start to get easier.
It sounds like your dog is very sick, and despite not wanting to put your dog down, I think deep down you probably know its the right thing to do. I honestly think it would be harder to continue to watch your dog suffer.
Try and spend lots of time with the dog tonight and enjoy the time you have left. Tomorrow will be very hard, but I found that the best coping mechanism was remembering all the fun times with my dog, all the silly things she used to do, and just looking at pictures and stuff.
Good luck with everything tomorrow!
