I suggest writing a plan. That will take the stress off trying to restrain yourself every day. Just stick to the plan and don't worry about it. Do get Combatting Cult Mind Control. That book is for you, not him.
There are ways to ask questions that don't set off the cult radar. You may comment on the television series, "Breaking Amish" for instance. Not Witnesses, but with creepy parallels. I got husband to watch a full episode before he clued in. The series is most effective in flashing a scripture, which hubby would agree with, and then showing how this most literal of religions let the scripture play out in real life. Which, horrified, he did not agree with. He got really quiet. Now, when promos for the show flash up, he rants about how stupid it is and he won't watch it any more. Home run.
It sounds like your man can empathize; encourage this wherever you can. "Put yourself in my shoes", or "Imagine how this is making me feel", will pull him out of the cult mindset and really think about how this is impacting your lives.
Never, ever remind him he is breaking the "rules". I did this once and now hubby excuses himself for the anthem at baseball games, something he used to love to do. The more your hubby does natural things, the more natural he becomes.