This is a difficult one which I have read with great interest.
If I may, I would like to offer some suggestions.
If you have decided that the relationship has run its course then there is not much we can do. If, however, you would like to win your partner back from the Watchtower then you will have to be clever. Because they are. Make no mistake about that. I do not say that they are wise but clever in a deceitful way. You will need to play them at their own game by showing your partner (and them) that you are a reasonable honest person who wants the very best for your family. That is your priority! It is your family, not theirs. If you get angry or unreasonable then you will prove them right in your wifes eyes and reinforce her faith in them and what they say.
They are very slippery people to deal with and it is never easy or straight forward but they can be outwitted I assure you.
May I offer you some hope. My wife was raised as a Witness, became a regular pioneer (full time minister) for some years while I was serving as a ministerial servant for a number of years. I decided to leave as the double standards became more apparent. Over the course of about five years (yes five) my wife decided for herself that she did not want the truth (lies) any more. Now she hates the Watchtower more than I ever could because she feels so deceived.
The point is that you have to be patient and learn to play the game. Never argue with them. Because once you engage them in an argument you are unwittingly giving acknowledgement of their lies. Dismiss what they say with silence. Treat what they say as ignorant, uneducated nonsense which is all it is.
Others may have won victory in other ways and I would never say that mine is the only way but it worked for me. I wish you the very best.