I like it Carlos. So long as you know for certain that what you are saying about how she felt is accurate. I'm not really seeing how this letter could hurt you. Maybe some other folks could.
Are you prepared for whatever her response might be?
She might blast you. She might say thanks for understanding why I don't want to be with you anymore. She may ignore it.
Are you ready for any of the above, particularly a blast of anger? How about a blast of anger expressed abusively? (That has been her recent pattern. F__ you, you abusive blah, blah, blah.) What would you do then?
But it is a beautiful letter. It's one I would love to receive.