She may be trying to truly help you become a better writer (or at least her opinion of better.)

I have a friend that writes and publishes his own ebooks on Amazon and readers and critics alike are merciless when it comes to the smallest typos. She really is helping you by pointing out that you could write Shakespearian-calibre stuff, but without proper grammar and punctuation you are toast.

Try to stick with it and take her advice to heart. Even if she is just a mean b**** she has still helped you become a better writer. I'm sorry that you are triggered though. Lots of people in the world unfortunately don't get it when it comes to trauma.