Stirring up old negative memories is not a good thing to do as it makes it continue in the "time fabric" it's much better to see them with comprehension and detachment and stop bringing them up all the time, living in the present and create the future is a better option. Once and a while we all have a tendency to do so but it is not constructive,when it happens to me I immediately try to calm down and see them from another angle, outside of myself without emotions.