You talk of "sending a letter to friends in the congregation" , if you D.A you will not have one friend in the whole of the JW/WT world.
They will no longer think of you as alive, let alone as a friend. Think carefully before going ahead, I too felt a tremendous desire to D.A , I felt that it was dishonest to remain ,even tacitly, as a JW.
I am so glad I did not D.A, my extended JW family still talk with me, the younger ones are free to approach me with questions,and any of the JW's I meet are free to talk in a normal way.
I can still keep track of developments in the lives of lifelong friends, even though in reality I am dis-associated by virtue of not attending, and not believing, but not having the label DA gives me greater freedom than having their label.