Flaubert's biographers seem to accept it, though. In the original French it's "Madame Bovary, c'est moi," and it's been translated in varied ways by biographers. I've seen "Madame Bovary, it is I"; "Madame Bovary is myself"; and "I am Madame Bovary," in addition to the Davis version you gave. You might be able to find out where Flaubert said it if you search for a translation other than Davis' or for the original French. Thank you for such a thoughtful review with such careful attention to detail!