How do you forgive and forget?

I forgive the offending person for me, not for them. If I hold a grudge, I lose sleep over it. The other person obviously doesn't feel badly about what they did, maybe even doesn't think it was a bad thing, they were just looking out for themself. I write a letter explaining just how something hurt me, how it has affected me, and I forgive them in writing. A few days later I read what I wrote and then throw away or destroy the letter. Rereading it is important for me, it lets me "see" the actions in the third person or as an observer. It is easier for me to see if I created the problem in any way reading it. Then it goes in the ash can. Forgiving them doesn't require me to speak to them or let them have any space in my life. It just requires that I let it go.