It’s a memoir, and as such, entirely subjective. Anyone who reads memoir should know this. Memory is flawed, interpretation of events differ depending on who is telling the story, the chronology of events are mixed up or deliberately changed to help the narrative flow etc etc. That’s what is meant by ‘it’s a little bit true and a little bit not true’. Read memoir for your purposes, to help you in your life, or to be entertained or whatever your reasons, but don’t let your experience of a text be marred by whether it actually happened or not.
Unless it’s an appliance manual for a pressure cooker or a technical report that you are using to build a bridge. The purpose of your reading is what matters most. Therefore, people with brain illnesses who used this memoir as a reason to give up their meds and start walking with heavy backpacks in the hope of a cure should be rightfully upset that they took ‘Raynor’ at her word. But they probably also shouldn’t have made such a decision based on one woman’s subjective account. The same goes for people who only enjoyed this book because they believed the author to be a perfect victim of a financial scam with no hand in losing her home.
That’s what is investigated in literary (and yes, the dreaded postmodern) theory. The relationships between writer, narrator, editor, language, genre, purpose, reader and how these, together, produce ‘fact’ and ‘fiction’.