If the nun said what you remember her as saying, she was teaching heresy.
She may have been ignorant of the facts herself, and passed this on to at least one classroom filled with many students. Those with two Catholic parents had no reason to grieve.
I brought it up at the dinner table that evening...I was upset by what I had learned that day, I don't remember what my intelligent mother said, but she completely relieved my mind.
Yes, I do remember the experience, and I'm sure others have stories of their own to tell.
In fairness, I have to say that I received an excellent education, by the sisters, through my twelve years of Catholic schooling. Thank you, Sisters!