Loss of Father & "Complicated Grief"

Hello, this is my first post and I am wanting to hear back from those who might share any similar experience to me, or offer any advice or words of wisdom?
I lost my father (as I knew him) to a massive hemorrhagic stroke about 2 years ago, while he was overseas on a business trip. My mother and I had to travel to a foreign country to help stabilize him and then med-evac him back to the states. In a nutshell, the experience itself of traveling to this country, seeing him post-op without half of his skull, seeing him suffer tremendously on the brink of death, was extremely traumatizing to me.
He has now been in a rehab/nursing home since then, going back and forth to the hospital with infection after infection. There are periods of stability, and then another infection will happen and he will have to go to the hospital. It’s back and forth like that.
He can’t move the right side of his body, he can’t eat or swallow (on a feeding tube), he can’t speak. . .there has been little to no progress over these long months, which have now dragged on to two years since the stroke.

He told me in a conversation a few months before his stroke that if he was ever in a situation where he was hooked up to machines to “pull the plug”.
I know my father – he would not have wanted to end up this way and to be forced to endure life like this. It is no way to live.
I don’t live in the same town as him and my mother and at my last visit a year ago, I was so deeply disturbed, as I saw that he was not coming back as we knew him.
That’s when the grief hit me really hard for the first time since the stroke.
I was so close to my father.

My mother is holding on to him and does not want hospice, although many doctors have suggested this to her. I keep praying that he will be released to end this suffering and torment I see him in.
The longer this goes on, the more tortuous it feels psychologically for me. I am aware at all times that he is suffering and that he is forced to live in this situation hooked up to machines. But I am powerless here. My mother is in the driver’s seat.

Does anyone have any advice about what to do in a complicated situation like this?

I’ve been told that this kind of thing can go on for a long time and so I have been trying to grieve on my own – as if he has already passed. Because for me – he is gone. The person I knew is gone. But it just feels like an endless grieving. . . I’ve been told it’s a form of “complicated grief” by counselors.

Would love to hear from others who have experienced anything similar or who might shed light on a complicated grief situation. Thank you.