06,
Growing up in an abusive environment is awful. But you can overcome this with time, distance, and help. I have been there and now lead a happy life free of that past.
But you seem more concerned with committing the "unforgivable" sin. I worried about this at one time. I am going to pass on what helped me gain some perspective. An elder told me that if you truly had committed the unforgivable sin, you would feel no remorse over it. You would not be feeling guilty and worried about eternal consequences. Since you have faith, you need to pray and ask forgiveness, and then forgive yourself! Coming from the background of abuse, that is not going to be easy...that's where counseling helps. Not counseling at the Hall, but with a trained professional.
My concern for you is that you are just going to give up. Please remember you are a worthwhile person. The people who have hurt you and abused you are not the ones you should be listening to. Take your dad's advice and get away from your mother. It will be hard, but you can do it! Keep coming here, read our stories and you will see many of us have shared this experience. We understand and are here to help.