This is HUGE - this power play is for the highest, rarest, most sought after stakes a dub can claim - a Baptism !!
The gloves are off, principles will be deflected, rules ignored, loyalties broken - the cult wants your boy and you my friend, are going to be thrown under the bus. It's time to burn bridges or get crushed.
Getting crushed is the cults way of shutting you up and having a chance to replace a liability with someone young and foolish...oh how they love naive youth.
You're already on their shIt list as a possible fader = (apostate) -possibly the reason your wife wants to be ever present - so you don't disuade the boy from the cults branding at which she will be centre stage.
ANY statement you make to the elder involved will be the first witness to your apostacy. A second elder will for certain stick his nose into this business and he will be the second witness to any little thing you drop that can be construed as apostasy - you could be DF'd and under a bus by next week. Then you have NO SAY AT ALL -silence of the lambs..
However- this could be the time to exercise your legal right to religious freedom -(something they are totally un- prepared for). You have already successfully abandoned service, tm school, commenting at meetings and the public declaration of field service. If you have a lawyer write a letter informing them that you have exercised your right to religious freedom then you are immune from eccleciastic discipline from the elders, they cannot form a judicial commitee, nor can they disfellowship nor disassociate you.
You will be shunned of course - but you are expecting that anyway, right?
Since you could not be subjected to disciplinary action (because you had repudiated their control with that letter), you control your actions , not them. If your son sees how these hyenas react to personal religious freedoms of ordinary people like his own father , he is less likely to place himself under the cults control.
You might research a man named Norman Hancock who won a sizeable settlement from the Mormon church for interfereing with his abandoning that similar faith.
Good luck in any decision you make. Please keep us informed, your's is an interesting situation indeed.