I understand what you went thru. I was in a similar situation with a friend of mine. And his mother.
A failed attempt with xanax. Under cocaine influence. Never regained concience again. Six, yes 6, years in a coma.
His insurance covered every single penny. More than ten million dollars.
He had bipolar. Otherwise a completely healthy person.

I was the one holding the hot potato. Since I visited most every day and there was no one else, I had to make the decision.
I won't go into details but it was a fight to change protocol. I did win. He went in a humane manner. But left me in pieces. I lost the battle with God.

I understand it wasn't easy, even if you had family concensus. And he was terminal.
Don't know what else to day.