Mental cruelty is a state of mind. The feeling of deep anguish, disappointment, frustration in one spouse caused by the conduct of another for a long time may lead to mental cruelty. A sustained course of abusive and humiliating treatment is calculated to torture, discommode or render the miserable life of the spouse. Sustained unjustifiable conduct and behavior of one spouse actually affect the physical and mental health of the other spouse.
Article source: https://medium.com/@Indiadivorcehouse/mental-cruelty-intro-how-to-33578fa75009