My favourite ever book is Some other rainbow by John McCarthy and Jill Morrell. It does deal with mental health because he kept his wonderful sense of humour despite the inhumane circumstances he found himself in. I've read it dozens of times, really, and it makes me laugh out loud and sob equally. Highly recommend it.
I love true stories. I have a mixture though. I like true crime aswell as Harry keeble's books. I also like reading about mental health too but there seems to be very little true story books about that. Any suggestions?