Some key books and author's:
Opening Up: The Healing Power of... Confiding in Others
by James Pennebaker, Ph. D., is a clear explanation of his theory which has been repeated in several research studies that if done correctly writing resolves traluma. It has to get worse if it's going to get better.
At a Journal Workshop : The Basic Text &... Guide for
using the Journal is Ira Progoff's basic guide for intensive journaling