This is really tough. It's also, unfortunately, really common.

My professor who was murdered by her ex-husband had been abused by him for years and years. She was a college professor who had written a book of feminist criticism. Knowing these things is not proof against getting sucked in.

She is, of course, making all sorts of wrong assumptions and unwise actions, but you know this. I don't think you're overreacting. AT ALL. But until and unless she's ready to listen, probably the best thing you can do is be there for her until she gets to that place.