The Three Forms of Closure

For her traumatic wounds to heal, the victim of abuse requires closure - one final interaction with her tormentor in which he, hopefully, acknowledges his misbehaviour and even tenders an apology. Fat chance. Few abusers - especially if they are narcissistic - are amenable to such weakling pleasantries. More often, the abused are left to wallow in a poisonous stew of misery, self-pity, and self-recrimination.
Depending on the severity, duration, and nature of the abuse, there are three forms of effective closure.
Conceptual Closure
This most common variant involves a frank dissection of the abusive relationship. The parties meet to analyze what went wrong, to allocate blame and guilt, to derive lessons, and to part ways cathartically cleansed. In such an exchange, a compassionate offender (quite the oxymoron, admittedly) offers his prey the chance to rid herself of cumulating resentment.
He also disabuses her of the notion that she, in any way, was guilty or responsible for her maltreatment, that it was all her fault, that she deserved to be punished, and that she could have saved the relationship (malignant optimism). With this burden gone, the victim is ready to resume her life and to seek companionship and love elsewhere.
Retributive Closure
When the abuse has been "gratuitous" (sadistic), repeated, and protracted, conceptual closure is not enough. Retribution is called for, an element of vengeance, of restorative justice and a restored balance. Recuperation hinges on punishing the delinquent and merciless party. The penal intervention of the Law is often therapeutic to the abused.
Regrettably, the victim's understandable emotions often lead to abusive (and illegal) acts. Many of the tormented stalk their erstwhile abusers and take the law into their own hands. Abuse tends to breed abuse all around, in both prey and predator.
Dissociative Closure
Absent the other two forms of closure, victims of egregious and prolonged mistreatment tend to repress their painful memories. In extremis, they dissociate. The Dissociative Identity Disorder (DID) - formerly known as "Multiple Personality Disorder" - is thought to be such a reaction. The harrowing experiences are "sliced off", tucked away, and attributed to "another personality".
Sometimes, the victim "assimilates" his or her tormentor, and even openly and consciously identifies with him. This is the narcissistic defence. In his own anguished mind, the victim becomes omnipotent and, therefore, invulnerable. He or she develops a False Self. The True Self is, thus, shielded from further harm and injury.
According to psychodynamic theories of psychopathology, repressed content rendered unconscious is the cause of all manner of mental health disorders. The victim thus pays a hefty price for avoiding and evading his or her predicament.