YES YES YES! I have MAJOR issues with letting things go.
I am always remembering things that bother me in personal relationships. It doesn't even have to be something said or done.. it can just be a glance- the way someone looked at me, or a physical response to something I said. When I was 14, an 8 year old remarked on a physical characteristic and it saddens and angers me to this day.

I sometimes fantasize about contacting these people and making them "pay." There, I said it.

I ruminate all of the time about what I should or shouldn't have done or said differently. Replaying it over in my head. I could go on and on but I won't.

The bottom line: No, I can't help you with this, except to say that you are not alone! Maybe someone else can help us both!