What is the origin of the idiom "be cruel to be kind" and when to use it?

The origin of the idiom "be cruel to be kind" can be traced back to Shakespeare's play "Hamlet." In Act III, Scene IV, Hamlet tells his mother, Queen Gertrude, that he will be harsh and cruel in his words and actions in order to help her realize the error of her ways. Over time, this phrase became more widely used to express the concept of employing tough love or harsh measures for the ultimate benefit or well-being of an individual. It is often used in relationships, such as between friends, family members, or mentors, where individuals may need to confront difficult truths, offer blunt advice, or enforce boundaries for the long-term benefit of the other person.