Confused

Reading some of the posts on here, I realise this movie is confusing, but I only caught the last hour and had to keep turning down the volume because of the screeching harpie with long dark hair, whose scenes it seemed consisted of her screeching, screaming, whinging, at every opportunity, I was so happy when she finally got bumped off in the bedroom. However, I have to say I didn't understand any of it, although it looked pretty decent movie. I am trying to find out, was Kurt being molested by his father? Or did the father kill the mother, and blame the son. When the mother is goes in the bedroom, there is someone behind the door with a baseball bat. Was that the father?