One good place to search for information on how children handle overwhelming doses of negative affect would be the literature on dissociative disorder. I suspect that there is a lot available through a Web search engine. As for books, start with any book that has the name of Richard P. Kluft in the title and you'll be off to a good start. Kluft has done more than anyone to call the attention of our field to the way children respond to trauma and abuse. I believe the best reference bears a title something like "Childhood Antecedents to Multiple Personality Disorder" and was published by American Psychiatric Press about ten years ago. Perhaps one of the lurkers on our Forum will have an even better suggestion.