Odd as it seems, punishment keeps a blackmailer in a strong emotional connection with you. In creating a highly charged atmosphere, blackmailers know they are activating the target's feelings for them, and even if the feelings are negative, they've created a tight bond. You may resent or even hate the blackmailer, but as long as your focus is on them, they haven't been abandoned or discarded with indifference. Punishment keeps a lot of passion and heat in a fractured relationship.
-- Susan Forward with Donna Frazier, Emotional Blackmail, p. 98