"he never hurt physically" so psychology attack is ok? Mental health is no joke, the author has gone too little too far with this character now the only redemption Arc for him should be death.
So he's putting an act so that she can at least live normally on earth, he prob is scared for himself and lily, that why she shouldn't know, who knows when sis is watchin... still cruel. What on heaven of a monster is her big sis.