What is Sakshi blacking Raj with??

Why is he keeping shut?? what proof is he talking about?? What tape?

I think he might have killed his brother(dev's father). And sakshi video taped it.

she must have proof against arnab's murder

it has to be something connected to murder of sakshi's husband
may be he was the one to burn the place n she recorded it.

Nandz feels you read my mind...I was exactly going to write the same thing. I think Rahmat khan had some evidence about Raj killing his elder brother and Saksi being Rahmat khan's wife came to know this and saw an opportunity here to become rich. So she promised Raj that she will destroy the evidence and when Raj turned down her she started blackmailing that she has not destroyed the evidence completely but has a copy to herself.