Ending theory...
I dont know if this has already been discussed... But Andrew's last words were "Which would be worse; to live as a monster, or die as a good man?"
I get that it's a window into his dilemma, his disorder... But he shouldn't KNOW that if he's living in a world of denial... Like... He's essentially telling his doctor, and the viewer, that he's CHOOSING to live in his fantasy, which means he's conscious of it... I feel like that sorta flies in the face of what we know of disorders like Multiple personality disorder, or schizophrenia... In such cases, yes, long ago, after experiencing a trauma, one can tell themselves it's not real long enough that they disconnect from reality and act as if it never happened, create an elaborate story that explains away everything in their current reality... But the movie is suggesting that this decision is far closer to consciousness than what we know of these types of mental health conditions... It's as if he said to his doctor, yes, I know what I did, but I'm gonna go ahead and play out this fantasy anyway, just so I can keep my mind occupied on something other than the fact that my wife killed my children, and I killed her out of (understandable) rage...
I do study psychology, and I'm by no means an expert, but I really do feel like this doesn't jive with what we know of dissociative disorders... The whole POINT of dissociative disorders is that they completely hide the truth from the sufferer... So there's no logical reason that Andrew would know, consciously, that he's a monster, and thus choose to live as a "good man" in denial.
You know what I mean?