I hate to advise an adversary-type marriage.
If she wants to play hardball and "turn you in" for saying "F" or for having doubts,
then you have a trust problem.
If it were me:
I would tell her that "We are going to couples therapy."
I would tell her that her refusal will result in her loss of spending money and use of the
car for meetings. It would further cause her to see who knows the JW rules on
headship. I would take over the budget and keep her so tight that she can't stand it.
No Starbucks or nothing for her. All she would have to do to let me fade quietly is
attend couples therapy (by a professional, not a JW elder) and learn to keep things
about you from the elders- just let you stop going and not report you. Anything she
reports, that would make me resort to full application of the headship principle.
Now, I avoided that circumstance by being kind and talking to my wife about trust
and loyalty. My wife understands that she doesn't have to report me, but that doing
so is a violation of our trust. She knows that I have to face Jehovah (or WTS) on my
own for my actions. A couples therapist should help her to see that.
I know the likelihood is that she will refuse, and she will tell the elders what you are
doing, but if you don't sin, all she can report is that she needs a ride to the hall because
you are not coming and won't let her use the car. All she can report is that she cannot
eat out or buy new stuff. It's not a smooth road, but neither is the one you are on.
I am not in your situation and I can only say what I would do. I cannot say that it is
the best thing for YOU to do.