Hmmmm! My father was 19 when he landed in France during WWII. He saw Dachau 3 weeks after it was liberated. You CANNOT UNSEE what has been seen. He saw the furnaces. And the citizens of Munich were forced to see them so there would never be any question about what happened there.
Stupid Egyptian. (he knows better, he is a Liar).
I know a man who helped liberate some concentration camps as well. You can tell that he still has to deal with traumatic memories. As you said, what has been seen cannot be unseen.