Thanks guys.
We didn't want to have her poked and prodded anymore. She was in pain, throwing up daily, and we opted to just release her from the pain.
She was curled in my lap while the vet put her down, exactly where she would have happily spent every single day. Is it bad that Rainbow Bridge holds no condolence for me, since there are no people for her to curl up with there? I can't help but think that she wouldn't be happy there. All those other animals to pester her and no laps.