If your life, and standards don't offend JW's, then writing a DA letter is wasted. What you need is just a time out from the belief system. Just act peacefully with them while you distance yourself from them. This makes it possible to allow peaceful future returns to some friends that you may respect, and have missed.
If your life or standards are in conflict with their belief system, write the DA letter. But, the less written, the better. You, don't want those who will read it, to hang you on everyword that they may missinterpret.