For victims of horrific abuse or trauma denial can be a way of survival.
I am not a doctor either. But life experience has taught me it is possible to pretend (even to yourself) that something never happened even when it is still going on.
Ask anyone who was/is beaten by a parent or spouse, was a prisoner of war etc.
I think denial can very well go on for a lifetime.
it can, but it shouldnt
certainly not in cases like this