I have recently gone on a reading binge of H2H self defense books that are not from a martial arts perspective, but from people who train professionals who are likely to encounter real violence and need to be able to dependably deal with it. Some of the books I've read stand out. I have seen some people here mention Rory Miller and I have long been a fan of his, although his first book, "Meditations on Violence" is a hard read. He even admits his later book, "Facing Violence" is much better and perhaps the best thing he's done. His experience as a career corrections officer has gotten him in a lot of altercations with hardened criminals. I also like Tim Larkin's book, "When Violence is the Answer."
But the best book I have read so far is Varg Freeborn's "Violence of Mind." Freeborn grew up in a family of violent criminals and at 19, went to prison for stabbing a guy who was trying to kill him. He claims that between his upbringing and prison, he has been in over a hundred fights that had deadly potential. He has shot people and been shot. He has stabbed people and been stabbed. But he turned his life around, got his rights restored by the courts, including being able to own firearms. He threw himself into the study of the martial arts, including H2H and firearms. He now teaches security personnel and police, tactics to deal with violence.
What Freeborn saw a need for in martial training is mental orientation towards violence. He said he learned great techniques, but the mental aspects were either not taught, glossed over or taught wrong. He felt many, although certainly not all, instructors have not dealt with with violence and have a lot of wrong ideas about it. What he learned on the mean streets and prison was that handling violence is 80% mental and your worst threat is most often someone who has no formal training at all, but who knows violence very well. The mental aspect is way more complicated than I imagined. The fact that you and I are not hardened criminals puts us at a disadvantage, but there are ways to bridge the gap. You won't come away from reading his book with that all solved, but you will be able to assess where you are at in relation to violence and you will know what you have to do.