For me, personally, under the scope of the Forgiveness and Compassion/Lovingkindness meditations in my early days, I revisited everything I could think of that was an uncomfortable thought. I revisited all the little childhood things that I did that were not so good, I revisited my speech that was not good, my actions that weren't so good. From childhood, teenager, adulthood, I revisited every one of them a number of times until I felt okay with it. Until I felt that it wasn't me anymore. Until I realized that, hey, look around the world, there is a twelve year old boy right now grabbing a candy bar and sticking it under the shirt and racing out of the store. There is a fourteen year old right now who just swore at somebody with all the evil intend they could possibly do. There is an eighteen year old right now who is a bit tipsy and floors a friend at a party.
There are all these people, and more, all around the place. I was once one of them.
So I went back to every one of those occasions, I had Compassion/Lovingkindness for who I was, who the other people were, I had Forgiveness for myself, I had Forgiveness for the others if they had done something that was also negative. I opened, I softened and I kept going back, and I kept going back until I was pretty sure that it is okay. Once in a blue moon I like to think about some of those difficult people. It's nice, it's nice to know that I can say the Compassion/Lovingkindness phrase without pausing.
Have you ever noticed that when you are doing your friends and family the phrase might go, "May so and so, so and so, da da da, find peace of mind." And then the next nice friend or family goes, "May so and so, da da da, find peace of mind." And then when you bring up somebody you don't like it's, "May (clearing throat), so and so (clearing throat), find peace of mind." There is a different quality in that Compassion/Lovingkindness wish if you are still holding on to your aversion. But when you are able to do that wish as easy for that difficult person, as you can do it for your family members and your loving friends then you know, "Hey, that's nice, I think I have let go and if not totally, probably 95% or more".
So it does pay to revisit those old difficult situations with other difficult people, etc. To go back with not only the forgiveness meditation but the Compassion/Lovingkindness mediation, soften and try to forgive, understand that we are all ignorant in some way, we made mistakes.