The book I am talking about is "The Gulag Archipelago"
See the screenshot (marked text) first. If the book has the power to change your memories so you can't distinguish between what you experienced and what you read, isn't that basically manipulation?
I know that something similar is possible for example with altered photos of you childhood that can trick your memories of the time, for example some object that you were told to have but you didn't.
It confirms that, for the anti-communists, the historical facts are not what is actually important, it's only the "feeling" they get when thinking about socialism that matters. That they not only try to convince others but even themselves to believe that things happened which never actually did, merely because it validates their emotions.
This is indicative of cult-like social conditioning, in which you are told to reject even your own memories when they don't confirm to the cult-endorsed narrative, and replace them with the fiction the cult tells you is what you actually experienced. Unfortunately this is a common phenomenon in post-socialist countries nowadays
You will encounter people who lived through those times and who were perfectly happy at the time, but who have been so socially and psychologically pressured year after year to accept the narrative that communism was terrible and they were actually oppressed, that eventually they internalize this to a point that it changes their memories.
It's a form of mass psychological abuse.