I too, am very sorry for your loss. It's difficult enough, without the staff adding to the anxiety.
One time I had to use a vet that was not my own. That was a clinical, cold experience. No sympathy or emotion from the vet in attendance. I still remember that to this day, even though it was probably ten years or more ago.
The vet I use is very empathetic. Handles it with care and concern. He's great.
We, too, have an ER vet. About 6 years ago, I had to take one down there at midnight. It was time to let go. It was handled very nicely - they have a separate room with a sofa I could sit on and hold her. It was more like a home euthanasia would be -- not in the clinical environment.
But even in the clinical setting, which is what most vets have, it can be done in a caring way.
You are right to be upset by the way your situation was handled.