My wife is the same. Very well read, but never learned the pronounciation of her fancy words.
Imagine the look on her face when I explained that the "hors d'oeuvres" she read about in books are the same thing as the "or durves" she was serving at the party.
I had the opposite, I always thought the word "grandiose" I saw in books was the word "grandeur" that I hear people say, so I always read "grandiose" as "grandeur" and thought "grandeur" was spelled that way. Whenever I heard people say "gran-di-ose" I would pipe up "uh, actually, it's pronounced grandeur, the s is silent".