The act of writing it can be cleansing. The act of leaving it behind for others to find can be vengeful and vindictive. Our thoughts and feelings are only a snapshot in time. If we typically write things down when we're upset, angry, or hurt we may not be writing our true feelings about a situation or a person. Of course, nobody would know that except the author. Snapshots out of context can be hurtful if there is no opportunity for further clarification.
Sooo, if (God forbid) your soul is about to take flight, please think about what you might have written down over the years and think about what it might mean to those left behind. Take it from me, a survivor.