Milsi may be rough. He may be violent when he is angry. Prachi knows that much better than any one else, being the recipient of many a shove and push and shaking of body till her bones are all rattled. Yet, he has never ever slapped her even though he had raised his hands to do so. That privilege strictly belongs to Ayesha and Ayesha alone. He has not hit her once but twice - once when he realised she had married Neev and again yesterday when he came to know she was the brain behind Ritwik's kidnapping.
On both the occassions the slaps were for her betrayal. The first was for betraying his love and the second was for betraying his friendship. Strangely, even though he believed Prachi had betrayed him by having a baby out of wedlock, continuing her affair with Neev and pretending to love him inorder to smuggle in her child, he still did not really slap her. There were other forms of torture he meted out to her. But in Ayesha's case he slapped her on both occassions. In a way I think this betrayal to him was far worse than what he thought Prachi had done to him. Here is a woman he thought he knew well from childhood - a person he thought was the only person he can trust, the only person he can rely on, the only person who understood him. Finally he has realised that person neither cared for him nor his family, never understood him, was totally unreliable and was the source of all his pain.
I can only imagine his pain in knowing that his best friend has been his worst nightmare all along.