Sometimes it can be very therapeutic writing letters like that. I say write it and burn it or file it away somewhere. I wrote a big, long letter to W and kept it, I found it months later and thought "holy cow am I glad I never gave this to her" LOL! It's surprising how much our thoughts about things change over time. I think it happens so gradually that we don't realize it. Sometimes those letters help to remind us how much progress we've made.