Everybody struggles with whether or not to write that letter. It is never a good time because all options suck. Stay in and watch over your shoulder while delaying what is often the inevitable shun gun that you'll have to face sooner or later from friends and family, or bite the bullet and get peace now but hasten the shunning. We left it up to a few things, one of which notably was whether or not elders called on us. If we could be left alone that seemed okay, but family already shunned us anyway. As soon as elders called on us we used that as a trigger to pull the pin and blow it all up. You'll likely never be truly ready because you are entering the unknown for you. Fear always lies in the unknown. In our case freedom and peace were what we unwittingly feared. It is awesome to loosen the chains and walk away, no longer caring about their judgements. We don't care what they say about us. They're of no consequence whatsoever because we're no longer tethered to them.
In all seriousness, you do have to weigh your options. Nobody can do that for you on here. You can't unring that bell, and that scared me to death. My wife was ready to pull the plug before I was, but waited and we DA'd together. If was awesome and life has never been more free. Even clients of ours mention how much lighter and happier we are. It's like you've been running a race with a 100 pound backpack on and you just sit it down and walk away.
As far as trying to get others to think in the org, that's on them. I'm not needed to save anybody. Nobody saved me or my wife. It seems most people exit on their own. Very few seem to have an apostate that was still in that somehow influenced them for the better. For most of has to be the right time and they have to have what it takes to battle the cognitive dissonance. Nobody can do that for them. People like go think they're going to somehow bring down the org from within like some sort of secret agents, bit it's still there and growing. We wanted to move on with our lives, not keep playing their games.