It's a good letter...
Too bad nobody will read the whole thing. JWs are trained to run away from anything even remotely critical of the Society/JWs. Most of those letters are going to find the trash can before being finished read. Some might read it, just to see how far you've gone "apostate".
But, on the slim chance that it might find someone who is already having some doubts, it may be the little push they need to get them to really look at things.
If it will bring you some closure, you should send it. Best case scenerio, someone might respond thanking you; worst case scenerio, most of the reciepients will shun you which you're already prepared for.