More or less my experience, except I've also got the sidebar of my mom being friends with his niece. They worked at the same school in the northeast, and they were really upset about what happened to him when I was a kid. I was always afraid of "tuberculosis" after that because it sounded scary and it killed Mandela.
Now, it IS entirely possible that what they were upset about was his incarceration, not his death, and my five year old brain processed it wrong when they talked about him being sick.
Couple things about that though: A) I don't think the SA government let it out that he had tuberculosis in 1988 until years later. Which doesn't necessarily mean I heard about it because he died from it. His niece might have been privy to that info at the time regardless of it being "let out" or not. B) I have literally zero memory of him being president, despite being super interested in world affairs and presidents.
It's possible the whole thing has a logical explanation that comes down to my memory being faulty, but all of this is super, super weird regardless.