I think she means that you might feel less anxious and distraught if you stop reading books about alters, DID, demons and all that kind of stuff, because right now they are really upsetting you and causing you problems. If you hadn't read that book you wouldn't be worrying about demons right now. When people are unsure of their own self and reality they can be very susceptible to outside influences, like - prime example - reading a book about demons and alters and then beginning to think you have demons and alters.
Sorting out your own truth is much harder when it becomes influenced by other people's experiences. It makes things messier and murkier rather than clearer.