Hey Frog, a millions times have I written what I really think to him. In my own words, no frippery, no jokes, no insults, no irony. And deleted every single one of them. Instead I started Dear STBXH, as you know, and the story still unfolds as I sit here, sometimes feeling sorry for myself, and sometimes not.
My counsellor suggested the writing of a letter and burning it (I didn't tell her of the Dear STBXH thread - started before she joined the Team!) but like you I was a bit dismissive of the idea. It felt a bit pointless to me too.
If there was a magic wand to heal the pain, I'd zap it on me and then hand it to you. But I am healing slowly, and I promise you, you will too.
The book I felt most persuaded by was 'Detach and Survive' so I'll add that to your shopping list. I want to look back in a year and say 'you lost control the day you left, and I never once let you take it back'.
It's okay to feel the way you're feeling. It's not okay to do something that you'll later regret. Don't bring any more pain onto yourself later for a little short-term gain now. It's the best advice I can give you.