It wasn't in English class but I will never forget a book we read in another class I can't remember the subject of that class for some reason. The book was "A Child Called It" that just describes horrid child abuse.
Something I read in history class and not English lit: Neighbors: The Destruction of the Jewish Community in Jedwabne, Poland by Jan T. Gross.
Most American students learn extremely little about how truly horrific the Holocaust was outside of the concentration camps and medical experimentation. This is a book about local Jews being brutally murdered by their own neighbors in Poland. Not by Nazis. Just your average person.
It was really upsetting but enlightening. Everyone should know about the atrocities that occurred throughout so much of Europe during that time.