One of the things we talk about in groups is dealing with healthy remorse vs neurotic guilt, and healthy vs unhealthy anger, and how these unhealthy patterns contribute to lower mood, increased anxiety and anger, and somatic problems which result.
I'm linking to two articles on forgiving self and others. At the bottom of each of these articles are further links to articles on forgiveness, including research as to how forgiveness has health and social benefits.
Hope you find them helpful.