How can one deal with a mother who mistreats her son's wife and her family, causing the wife to lose patience and threaten to inform her family, while simultaneously upholding filial piety towards the mother and not wronging the wife?

It is recommended to supplicate for the mother, asking Allah to rectify her situation, as supplication is answered. Enjoining what is right and forbidding what is wrong to her gently is not considered disobedience, along with explaining the seriousness of her cursing the wife's family and reminding her of retribution. If she does not stop, then the cursing should be away from the wife, or some of the mother's close relatives can be sought for help. If she persists in her behavior, then the wife has the right to have her own separate dwelling to protect her from the mother's harm.