I say quick fighting with them. Set some serious Boundaries.
You are the main provider...so make sure the bills are paid, savings is taking care. Make sure the wife and kids are in a safe environment. But if your wife want anything outside of those provisions...she will have to save from the budget you give her or look for a job.
Support your wife and your grown son being a JW. Don't discourage anything...if they are use to you disagreeing...this will get their attention. And what I mean by support...do not have any JW debates...that's what they want. I would engage with them lovingly on everything...but it they bring up religous discussions...just tell them that you do not want to discuss it. As adults we should have the right to believe however we want...but we must pay the cost to support it.
If the minor children have any hobbies or interest, please make sure they are able to indulge themselve in the activities and this will give you an outlet to take your mind off of the religious stuff. Believe me children having fun will definitely trump going to a KH.
Take this time to get know what you want...work on you. You want to take up an hobby, you want to take a vacation, you want to improve your education. Make this about you...not your family.
I suggest counseling...but start with yourself first...get clear on what you want. Then ask the wife if she wants....
But the focus should be on you and taking care of your family (those who want to work within your boundaries)