Thanks for all the thoughtful comments ya'll. I've definately have thought of the "growing years". I know I'm not the same person I was in high school and she may not be either. I also believe that her behavior was that of a typical, stupid, high school kid and admittedly I don't think any of my high school friends would have known how to deal with all the crap I was going through at that time.
I think that 9 years is a long time to still be upset over something as per your post, so I would suggest counseling to get over whatever anger you have left. By this time, you should be able to recognize what happened to you as bad, the friendship as lost, and to not have it bother you when you think about it (except to say that it is too bad that you lost such a good friendship at the time).
I believe I am over it because in my heart I know I've forgiven her and wish her happiness in her life. In fact I don't even think about this until I get one of her letters; they just bring up the memories of our falling out and how much it hurt me. In the past I'd just scan her message, throw it in the trash and forget about it after awhile. What's making me feel different this year is I actually just got her Xmas letter yesterday since she had sent it to my parents old address, it got sent back to her and then she took the trouble to look up my parent's new address (she stated this in the letter). Because she took the trouble to do this, I have thought about sending something back saying, "Have a happy life and I wish you and your family many blessings" and leave it at that. Hopefully she won't feel guilty anymore and it will give a "polite" hint that I don't want to renew the friendship.
I do believe that she feels guilty about what happened, hence the letters at Xmas. We had been friends for 6 years before this incident and all during that time J always had a hard time admitting she was wrong about something. It was like pulling teeth, so I highly doubt the first two letters contained an apology. By now she may have matured into a perfectly nice person, but I just can't forget what happened, how it made me feel, and how it colored my view of other friendships afterward (took me awhile to stop looking for HER betrayal in other people). I just don't want to rekindle a friendship where I have trust issues with the person because I don't want to deal with the emotional baggage that comes with it. I can forgive and move on, but when something REALLY hurt me I can't forget.