I know it sounds absurd - but it's easier to blame the child (Vansh) - than his own mother. He'll always see it as the stepson got his share from his mother - even though it was the mother who made the choice to leave him.
Rest I've no idea. If they'd made him an honest cop it would've been soon much better.
I agree with Sofna , the child mind will hate vansh not his mom , he thinks he stole his mom from him.
K is beyond redemption now , he kills ppl out of habit now.đł