That explanation really does not make much sense. Even in abusive relationships, women do not hand over their children on their ex's say-so.

In fact, I would say that they do not do that ESPECIALLY when in an abusive relationship. Why would she give control of her young child to someone who is abusive? The sister is under his control. She does not know that the father does not abuse both the sister and his son. Women do not lightly abandon their kids - they run away WITH the kids and go to a shelter, or back to their own parents' house. If she was prepared to flee, she could have gone somewhere unknown to him.

The story does not make sense. Does it make sense to you?

When people consult Dr Harley with the problem that a lie was told to them before they married, he tells them that the test that they should apply to themselves is whether they would have married that person if they had known the truth before they married. If the truth would not have stopped them from marrying, then it is in their interests to rebuild the marriage, now that the lie has been disclosed. (They can do what they want, of course, but that is his advice.)

You are not saying that this would have been a deal breaker before marriage. You are saying that you might have been prepared to marry her anyway.

That suggests that the way forward now is for you to see the child as planned next month, accept his presence in your life, and work towards having him live with you. If you cannot bring yourself to live with him, arrange more frequent, regular visitation instead. The point is that you do not have to give up the marriage - and effectively estrange yourself from your own child - as long as there is no contact between the first child's father and your wife.

She does not have to explain herself at all to him. However, the problem is that he might cut off access to his sister, and thus the boy. You need to establish your wife's legal rights. This arrangement is MOST unwise.