I also found found it incredibly hard to watch, and was also ruined me for days if not weeks. In fact, I think a certain part of me has been permanently changed.
And that is exactly why it is now my favorite movie. A lot of movies have moved me, but this thing did something I didn't even know movies could do.
I can echo the others. It's also my favorite movie, period. It is a movie that psychically assaults either vicariously through the characters and/or (likely and) through identifying with the themes of struggling with the idea of artistic experience, destiny, legacy, etc. Even if you don't "actually" believe in all of those things it's probably because you contended with these ideas before and came to some psychologically safe (ethically and philosophically coherent, at least internally) conclusion about them, but this movie really tugs at those deepest heartstrings and induces a reliving of the main character's struggles with those themes.
The first time I watched it I had to pause it halfway through... the next couple hours I was in a mental space that can only be rationalized as "schizophrenic". I thought everyone around me were psychopaths and I was the only sane one, but lived that in a more or less manic way. The only other piece of art that's had that kind of effect on me is the novel Naked Lunch. It's my favorite movie precisely because of how unflinchingly it plumbs those depths, those cracks, of the human condition and the anxiety of dying having not contributed enough.
Thanks for reaching out. I'm in a good place where I think I'm doing great. The description of the main character's negative attributes sounds identical to what my partner accuses me of. These perceptions are impossible to shake no matter the contrary evidence. In fact the person would rather ignore me than learn the truth.
So I identify with what I believe the character is struggling with in the film. I have no question about what I'm doing. My partner on the other hand has completely lost/never had faith after 30 years.
It's a tough spot to be in. Currently I'm discovering Jack Benny and there is a lot to learn.
And that is exactly why it is now my favorite movie. A lot of movies have moved me, but this thing did something I didn't even know movies could do.