In yesterday and today's episode, we saw that Sai had lost it in the grief of losing her son.
She was unable to control herself and use her senses.
Infact, this state of Sai could have also made her lose Savi as Savi could have lost her life yesterday.
In that case, didn't Virat actually do the right thing to bring back Sai to her senses?
Sai did need that slap to get a reality check. Didn't she?