I've helped 4 of my greys over the bridge, most emergencies that had to be at a vets hospital but my last big girl, Zoe, I was able to plan and have a mobile vet come to our home. All this vet does is euthanasias. It was the most peaceful passing of all experienced. They took her away in a black PT Cruiser. The cost was VERY reasonable here in central Pennsylvania $350 with a communal cremation and burial but her name is on a plaque.
I'm so sorry you had such an experience