The wording of the question is really fascinating.  It helps to bring out the layers of intricacy within the poem.  On one hand, the speaker's own past with her father is highly significant to the poem, casting a very profound impact on it.  The speaker feels trapped by the weight of her past relationship with her father.  It is to this end that the speaker feels the need to confront the ghost, resurrecting the dead in order to kill it in a manner of speaking.  It is not necessarily surprising that the events of their own relationship relate to that of the father being a Nazi and the speaker, the daughter, being Jewish.  In this paradigm, there is a connection between both in which the survivor must confront the perpetrator, the person primarily responsible for evil.  In the poem, one image which speaks to the historical weight of events in the past is the idea of a father who "bit my pretty red heart in two."  Another similar image was the "tongue stuck in my jaw" and the "barb wire snare."  In evoking Holocaust based imagery, Plath seeks to develop the idea of how the historical events of the protagonist's relationship with her father has created such an impact that the poem, itself, is a declaration of severance.  This helps to bring out how much of a violation there was in the relationship between father and daughter, and this helps to create a very weighty impact in the development of the poem.  In the articulation of "I'm through" there is the revelation that there can only be some hope of progress when there is a symbolic assassination of the malevolent force.  In this, there is a clear statement that the speaker's own historical events, the weight of her past, impacts the development of her narrative and her text.