Here's a short list of some of the books I recommend regularly:
Surviving Schizophrenia: A Manual for Families, Consumers, and Providers
Surviving Manic Depression: A Manual on Bipolar Disorder for Patients, Families, and Providers
An Unquiet Mind: A Memoir of Moods and Madness
Understanding the Alcoholic's Mind: The Nature of Craving and How to Control It
Stop Walking on Eggshells: Taking Your Life Back When Someone You Care about Has Borderline Personality Disorder
People of the Lie. (by Scott Peck. It's about sociopaths.)