Who said that it is only Kamili and Mangala? It is about all the weaker sections of people and who all cross his way.
He was also involved in some illegal business deals and was shown doing fraud and bribing a govt official - I think that has to do with land or something.
It is all about making money buying power and get away with what ever he does using that power and people cover up using political power and bribe people to shut mouths.
He has been doing all these from the time he was introduced. He wants to do them on a larger scale
Kamili since she knows better he is concerned about her exposing his deeds so he wants to silence her.
Nandini is insistent on going to police -She may tell that she is a child bride of Kundan and if that gets out Jagya's support is lost.
So he has every reason to feel threatened.