If you're interested in reading about DP you should try Feeling Unreal or Stranger to My Self. They're probably the best and most complete works to date on the subject.
As for other mental health-related reads, I'd suggest An Unquiet Mind, The Center Cannot Hold, Brain on Fire, The Brain's Way of Healing, My Stroke of Insight and The Body Keeps the Score. There's a good mix of first-hand accounts of struggle as well as some encouraging science mixed in to help you cope.