Raxxxx - Welcome to the board and bravo on learning about the lies of the WT. Writing the letter is cathartic, and may make you feel much better, and that's a good thing.
You understand you will be playing into their hands though by submitting it? Why not send it to as many rank and file JWs as possible, just slightly re-wording it to let them know that you love them, love God, etc, but cannot follow men anymore and must follow your Bible trained conscience? Then list your points, and tell them that you will never be afraid of telling the truth.
It will of course get reported to the elders soon, and they will have to try and deal with it. Be vague when they try toi investigate you- ask for a meeting to discuss "your doubts" and "get help". But prior to any annoucement that is made wherein all the Dubbs will be compelled to shun you there is a window of opportunity to Witness to them about the false prophecies and dates, etc.
Most will not listen, but a few might. We are here are we not? There are tens of thousands of JWs that are doubting due to these points you listed- and that makes it worthwhile to try IMO.
Also, if you can secure a judicial meeting with the brothers, you can record it, expose the lies to the elders who may one day wake up, and also put it online for all to hear-- One more stone piled up against the false prophets of the WT society.
Food for thought bro. Take care- you will make the right decision!