That's sad . Not a question for legal advise I'd say. May be some psychological-marriage counselling for both the spouses, though, my instinct doubts what it'd do really for someone who has embarked on such a disastrous path and the poison has been introduced .
Don't take any rash legal action (many lawyers would love to advice you to run a newspaper advertisement from parents to general public, disowning the children and spouse; my advice, don't do it). May be start creating/collecting evidence of some sort if, God forbid, in future, you need to corroborate your stand of being pressurized for separation from parents by spouse. Write e-mail to friends/relatives narrating this and seeking their assitance and intervention. Go to a psychologist/family counselor with your spouse, describe the issues and get a written medical/psycholoical advice of at least going to it with your spouse,if not entire facts. Install a call recorder on your smartphone and record any threatening or abusive conversation along with call logs/detail bills to substantiate the factum of calls such as date and time; record face-to-face threatening conversations using your smartphone.
Hope it never comes to that but if it does, how and why any of this may be used is for time to tell; best be prepared as you have been warned :(