I know that Dev was provoked beyond measure when he saw that Vishaka was trying to kill Radhika (by the way the strangling scene was extremely childishly directed)..........but I will go on repeating that his slap wasn't justified. .........the creatives know that they have messed up big time by introducing ONS and crap and so are trying to make up by using cheap gimmicks. As for what Vishaka did she should be dragged to the police station and put behind bars.............amma should also be put there.............but the creatives won't do that and will let these two would be murderers remain scot free for their own pleasure. I never said that Vishaka should be excused.
Dev's action in slapping Vishaka is fully justified. The shameless hussy is attempting murder by strangling Radikha and the slap is really really necessary to snap her out from whatever evil intention that is possessing her at that time. Theres no excuse in trying to kill or harm someone and IMO a mere slap alone is not enough to punish her for what she has done.