I wonder what it is they are preparing for. If it was a call to be together to survive Armageddon, that is one thing. A natural disaster like a hurricane, flood etc is something else .
Your decision to leave the WTS should have no bearing on what you do as a family in the event of a natural emergency. In theory at least, your wife is bound to you and must obediently follow your direction as family head. The congregation elders would have to supprt that view.
Now in the event that Armageddon were to strike.... the call might be for the faithfull to be together for salvation. That would be different. It is a pretty safe bet that that is never going to happen