How can one deal with a wife and her family who show affection and respect while cursing the husband and his family with insults, death, and burning, knowing that the wife repeats "Amen" to her mother's supplications?

The fundamental principle among Muslims is safety and well-being. Allah has forbidden ill-suspicion, spying, and seeking out faults, unless there are clear indications that arouse suspicion. If it is confirmed that the wife's mother invokes death upon the husband and the wife says "Ameen" to that, then she has done wrong. However, the wife's "Ameen" might be out of courtesy. The husband is advised to hold onto his wife, improve his relationship with her, teach her matters of her religion, and clarify that his right over her as a husband is greater than the right of her parents. He should also be a good role model for her. He is also advised to be patient with relatives and to respond to ill-treatment with kindness.