I wouldn't say they are insane but rather looking out for their welfare. I assume my statement of the boy being the only son is correct? So they don't want to be the ones filing the complaint because of their fear. If boy does goes to jail or has some repercussions, no one will be there to take care of them. If it passes without anything happening to the boy, he will try and leave them. Or it might turn into an even worse abuse for them. Thats the reason they want an outsider to file the complaint.I can understand that the boy is insane.
But why do you think parents are insane? And are you saying girl is insane too?
Ok
Yes I had a direct crude talk with him 3-4 months ago, I told him it's an unacceptable behavior and he wasn't in mood to accept his mistakes easily but when I gave him what I thought he had to admit whatever the reason maybe his rudeness cannot be justified and he had promised me not to repeat this behavior again.