After he heard what had happened, he was shocked. He was not expecting to hear that and that too about Roshni. When he looked at her he saw that she was innocent. You can also see his anger building up regarding who framed his wife. He got the most angry when she actually left, he did not react then bt we know he will after Roshni is brought back. Even at the end of the episode he was angry and determined to prove Roshni's innocence. Man he was so hurt and angry all at the same time. He could see that Roshni was hurting and we know Sid can't see Roshni hurt or in tears. It breaks his heart to see her like that because he loves her. He also knows that Roshni might have accused of him and said terrible things to him and that she has trust issues, but at the same time he is unable to see her wrongly blamed or accused. He is aware that Roshni does love him bt is not saying it. He also knows the reason behind her trust issue. Roshni has been betrayed more than once and had issues with DD for a long time. He understands everything that Roshni has been through. He might have been hurt by her words but he understands. The only thing is that their egos have taken over their minds & souls.
Since he knows her so well, he knows that Roshni could never actually do something like that to him. She would never cheat on him. Sid does trust Roshni all he wants is for Roshni to trust him. But we know now that Roshni will come to know that Sid has always loved her and there was never any abd intentions of his towards her.
While Sid is around no one keep Roshni away from him...not even divorce.