I learned about it kind of late. Having read all the books available at the time, I was reading through the Objectivist Newsletter and then the Objectivist in chronological order. The Objectivist back issues were expensive for a high school student relying on his allowance, so I was buying a year's worth at a time, and it took me quite a while to get to the big intellectual break-up.
I never had the "child of divorced parents" trauma that a lot of Objectivists did, and the whole "choose sides" thing was a bit confusing. I was just 17 and did not guess ANYTHING about their affair, which was secret from the world but openly discussed with their spouses.
However, I did hear someone outright ask Ayn Rand about whether it was true she had had an affair with Branden. It was during a question and answer period. I think it was at Ford Hall Forum. She said no, she had not, and besides he was not her type.
Well, that "no" was a lie. It sure fooled me. I don't mind, exactly. It really wasn't my business. But I bought the lie, and thought the question had finally been answered, now that she gave a definite answer.
In Leonard Peikoff's book, Objectivism: The Philosophy of Ayn Rand, he specifically says that it IS OKAY to lie in order to protect your privacy from snoopers.
I guess she thought so too.
Of course, once you tell me "I lie to protect my privacy," the next time you tell me anything about your private life, I am going to take it with some extra grains of salt.