The first step in meditation is letting go of the past and future to come back to this moment. This is hard to do sometime, especially when we hang on to resentment about something or someone in the past. We will be sitting in peaceful meditation then all of a sudden a memory about the past comes up. It stirs up strong emotion that takes us out of stillness. Instead of being in the present , we are stuck in the past with aversion ( Hindrance 2) as well. The past is the first thing that we want to let go of in meditation, and aversion is one of the biggest obstacle the prevents the mind from settling into stillness.
You can't change what has happened, but you don't have to relive it over and over. Not forgiving is a form of self punishment instead of the other person. It is imprisoning yourself in the past, a past with full of aversion...Listen to all