This is not a sudden move to butcher Savita's character, she's been shown like this in the past too. When Manav and Archana were first married, Savita tried and succeeded in controlling Manav she used to guilt trip Manav every chance she got and continues to do so today. Yes, there was a time Savita changed for the better but Manav wanted to be great and put a promise to Shravani over Archana and Savita's happiness, Manav was wrong to do that and he was wrong in the way he got married. I don't blame Savita for being angry but I don't find it fair the way she has treated Archana, tried to kill her and wish her dead. Savita crossed the line there and continues to do so by wanting her son to choose her over his wife. Savita is willing to forgive Manav for screwing up yet thinks the worse of Archana, despite Manav being equally at fault.