Oh, I feel your pain. I really, really do. Whenever I hear someone, or read something, that is not correct, it's like nails on a chalk board. If I don't know the person, I'll keep my mouth shut. If I know the person, I'll still keep my mouth shut. People tend to take offense at that because they feel you are making fun of them. Sometimes, perhaps you are. Other times, you're just trying to be helpful but they won't see it that way. They feel you are making them look stupid. Problem is, they've already done that (at least to me they have) and you're just trying to help. Not stupid as in, "Wow, what an idiot! How did you ever get out of grade school?" but stupid as in, "You just crashed the car into the garage freezer because you thought you had it in reverse, but had put it in drive." A totally stupid mistake that any person knows better than to make, but sometimes your brain just flips off for a second and you do something stupid.
So, I suggest you just keep your mouth shut on the issue from now on. Unless she starts doing it to deliberately make you mad, just leave it alone.