You have said this all so well, even better than I could. You should write about it.
It took me years to write about the choices I made and why I chose to become estranged from my father. I still rarely talk about it but writing about it seems to free my mind and make sense of the whys and hows.
I agree it comes down to boundaries and taking accountability. Many parents, especially the past generation, feel that their position as a parent exempts them from being responsible for any harm they cause, but that isn’t the way things work.
They gave birth to humans. Humans have feelings. And choices. A child doesn’t start out with any intentions to cut off their parents so if that’s a choice they made in adulthood, the parents needs to look closely at what part they had to play in that.