Letting Go

Recently I have been bothered about a relationship that has gone sour. Actually, it was more than sour, it was way past its expiration date, and I overlooked its curdled edges and acrid smell. It was a long standing relationship, but one that had little or no recent contact--and by that I mean several years.
So, how does a person let go gracefully? Sometimes, and I guess I was hoping that I could go this route, it just fades into an occasionally phone call and a holiday card. The semblance is still there, the possibility of restoring it to its former self is still possible. Unfortunately, this possibility was not an option for me, even though I was hoping it would be. The relationship ended with a series of nasty e mails, sent in shock and anger. It was on my part an example of no good intention going unpunished. I don't want to go into details, because that is not the purpose of this post.
My concern is after forgiving, how does one forget and move on? In today's New York Times, I read an article about closing doors. In some ways, the scales fell off my eyes, and I felt a sense of relief, which doesn't happen too often when I read newspaper essays. In essence, the article says that closing a door is the only option available in order to move forward. I have closed that door, and am not looking back.