I replied to a post here, since no response is there iam posting it here:
I feel it is real Kushan who died and this is Prem who is in disguise of Kushan.
He might have done a plastic surgery and a revenge due to the cheating Prateek did to him long back
Else what is the suspense after revealing the criminal in a thriller show?
They kind of revealed it but still not revealed it completely. That is the point of revealing it.
Prem actually planned to take revenge on them using Lavanya in the past by keeping a relation with her but since it got revealed and again he got so much angry due to that day of his fight with Prateek
May be Trisha is close with Prem uncle and shared her matters with him