I agree with others who recommend that you say nothing....just fade away. It may feel good to get things off your chest but the good feeling will only be momentary.
Most of your friends and family at this point, still want to be lied to. They want their "ears tickled" and they don't want to hear anyone say out loud what they already know. People at this stage are frightened and scared people will act irrationally in order to relieve their fears. This will likely include punishing you for being the one who made them think about things that scare them.
If you slowly fade away, you won't have to face this huge confrontation that you are dreading and if you do it right, you'll still be able to speak to your family and friends and possibly help them.
Trying to use normal logical thinking to handle people who are themselves trapped in a religious cult, won't work. You need to help yourself first before you can help anyone else. Fading isn't being cowardly...you are simply making the best of a crazy situation.
Again...think twice about putting anything in writing or sharing your plans with any JW. You already know what they think and what they'll do, why put yourself through that?