ずにはすまない

ずにはすまない expresses a strong sense of obligation to take action or to do something because of a situation or responsibility. It conveys that avoiding the action is impossible or unacceptable, and you must do it, often to make amends, fulfill duty, or prevent a worse outcome. It is more forceful than simply saying you should do something and is commonly used in formal or earnest speech when taking responsibility or acknowledging a necessity.