Cognitive dissonance can really take a toll on a person, especially if he's fighting it tooth and nail. I know for a time I was borderline mental because I was struggling trying to be a good JW and at the same time learning TTATT without hesitation. It took it's worse toll when I still thought I needed to go out in service and reach out for privileges. We both know those two personalities don't mix, and it takes a harder toll on some people. You never know. This could be a mental breakdown from knowing that what you have been telling him is the truth, yet him resisting and trying to maintain status quo in the JW world could have caused him to break down. I hope it is something as simple as cognitive dissonance finally taking it's toll, and not something more serious.
We'll keep you and you're family in our thoughts. I hope this turns out well for both you and him.