Previously no matter how angry he was at her, especially after the 1st MMS by RV. He still was always there for her. He made sure that no one had hurt her. He was even hurting the most when he was forced to divorce her, because he was going to be hurting his Roshni. He was able to live sad and lonely forever, but hurting Roshni was the worst thing ever for him. From the precap it seemed as if he was happy seeing her, though he did not show himself to her. Before though his revelation comes, I am sure he will either do or say things that will make Roshni know for sure that it is her Sid.
I don't know how many here watch KKB, but something similar is going on. In KKB, the female lead gets hit by a car then comes back making the male lead hate her. She changes her tune and acts as if she does not love him, only to get the truth about the villians who are out to harm him. The only difference here is that the male lead in KKB has no idea about who is out to harm him. And in JR Roshni is fully aware of the fact that Shabnam is out to harm her family and is the one who "killed" Sid. But the similarity is that Sid and Pragaya (female lead in KKB) are both pretending to be someone they are not. I just hope like in KKB, JR does not take months and months to unite SidNI again...