The scene shown yesterday, shouldn't be judged at any cost as that needed for the story or the particular situation or they wanted to show how mad/upset that selvam character was with that particular accusation or sivagami character's talk is unacceptable. We can stretch the general rules upto some extent for the sake of the story, can't completely demolish them.There are different ways to make the situation worse instead of make that selvam character slap a lady who is more or less his mum's age, happened to be his mum-in-law, infront of her husband and grownup kids. No matter what ever the reason, THIS CONCEPT IS UNACCEPTABLE AND SHOULD HAVE BEEN AVOIDED AT ALL COST.
The only outcome of that scene was selvam's character suffered fatal injuries, because that character fall from a summit of moral strength.
Nowadays in some of the movies, alterntive endings are available, like that if we can get an alternative episode for the previous one, that'd be really nice.