i don't plan on writing a letter, but if I did I think it would be for the sole purpose to plant seeds into those that might read it.
A few things that I would include would be a reference to Steven Hassans, Combatting Cult Ming Control and also a reference to "Cognitive dissonance" and how it would apply as far as doubts that have crept up and how CG made it possible to put it aside or dismiss it as a "Jehovah will reveal it in it's own time"
I clicked over and read your DA letter levingwt and it is well thought out.