What did the son do to the woman?
When the son is confronted with his dad (after his visit to the woman); the mother says that the son had "touched" the woman inappropriately and "touched" himself meanwhile (and sister, Peg, doesn't seem to be correcting the mother (how even anyone knows what happened before Peg opened the door is weird as well - maybe the son's own testament?). What one can se in the movie is that he never seem to touch himself and instead of "touching" the woman he is, while fully clothed, torturing her body with a pair of pliers (and the scars can't be explained by "touching").
What's up with that?