I was going to suggest perhaps a less harsh approach, until I read that he has corresponded before and you've gotten nowhere.
I take it that the softly softly approach did no good.
I really feel for you. Its a horrid situation to be in. You did set him straight on the abandoning Jehovah thing. You didn't abandon Jehovah, you abandoned lying men. There is a big difference.
GOOD FOR YOU!
Its important for you to express these things. I really hope he responds.
Only one error I can see - 67%of those raised in the JWs leave. Not 67% of all JWs.
Sirona