Snoop needs help

Hello my name is Nate and I come to you with humility. Snoop is my only son and 10 days ago my boy Snoop came down with a bad stomach ache. I took him to the vet immediately, and hydrated him nursing him back to health. He was doing good until 2 days ago he took a turn for the worse, and stopped eating (chicken.) He won't get out of bed, (only to drink water and to pee.) He's lost all his energy and can barely walk, (as I tried to take him yesterday.) He needs x-rays to determine if there's an obstruction or cancer; he also needs blood work. He may even require surgery, and I can't stand seeing him in pain. So he and I are at a crossroads, and I don't know how to sentence my only boy to die (because its the "Humane" thing to do.) I have 12 years of memories with him, and Im at a loss. I've never asked for help, (its humiliating to me) but I have to know that I did everything I could to save his life before our only choice is to put him down.