Lara, I am one of many intimately familiar with your situation; my RB kitty Jamara was 18 and had a growth assumed to be a tumor in her jaw under her tongue. We never had it biopsied because the vet thought she'd die in the process. We were liquifying her food and spoon feeding it down her throat for some time until we made the decision to end her suffering. That was over six years ago and I still remember it like it was yesterday.

You have to remember that's what you're doing, is ending Barney's suffering. He will be going to a place where that suffering is no longer. Wish him godspeed for all of us, and take care of yourself. to all of you who made Barney feel welcome and loved, and to Barney.