Are there meditations for forgiveness? I'm having a lot of trouble forgiving someone for something they did quite a little while ago. The repercussions of which I am still dealing with today. I feel a lot of anger and frustration when I think about what this person did, and it's very hard to ignore.

I have already spoken to this person, and told them how I feel about the situation - ultimately forgiving them, but it still troubles me internally.

What can I do to "purge" the thoughts from my mind and the negative connotations that come with them?

EDIT: I do not wish to forget what happened, only learn to better manage the emotions that are felt when recalling the incident.
Well this form of meditation is not well established or part of the more common meditation object but Bhanthe Vimalasiri does teach forgiveness meditation. The instructions are here: http://www.dhammasukha.org/forgiveness-meditation.html