Well, what was the driving factor of the force, what that force was, the nature of that force etc need to be scrutinized before giving the final answer. But for time being, this ruling could be useful:
2507. A man who divorces his wife must be adult and sane........ Similarly, a man should divorce of his own free will, therefore, if someone compels him to divorce his wife, that divorce will be void. It is also necessary that a man seriously intends to divorce; therefore, if he pronounces the formula of divorce jokingly, the divorce will not be valid.