Like it hasn't escaped my notice that people here try and directly relate Jehovah's Witnesses and abuse like there's an inherit connection? Based on what? Something the Bible says?
To oversimplify for you - the connection is the intense pressure for JWs to conform to Watchtower demands (X) invokes the worst emotional/mental/spiritual scenarios. Formula: JW + (X) = (worst emotional/mental/spiritual scenarios). For your case ... abuse.
The Bible has many laws and principles. But none of them are directly addressed to you or your Dad. In this case, since you live in the real world you are subject to reality and NOT ONLY your faith (Heb 11:1).
JWs are a spiritual nation within real nations of vast cultures and diversities. The big problem here that the Governing Body constantly ignores is - in this world the Watchtower enforced principles (including policies), according to its own Bible intepretations, has time and again failed when it comes to various realities or circumstances.
Your Dad should have NOT been appointed as elder in the first place. Since it has happened already, then he should step down and seek help for his past issues. In fact he should seek professional counselling - the ones he could sue, and not the quack psychologists at the KH. You should forgive him especially when he recognizes his issues. BTW, if he persists in the abuse, please call the real authorities.
And you young lady don't self-flagellate. Recognize the problems, avoid or solve them if possible.
Please read my carefully worded posts. These problems do happen in this world, but it also does happen to JW families. And it is even worse, because you are trying your best to fit all the Watchtower interpreted Bible principles into your life.
As JW I ask you this, according to Matthew 11:28-30, does Watchtower's guidance make your life's burden really lighter? If not then the Watchtower has failed to be the slave Jesus was asking for, because it has failed to be the model for the Christ.