The rude, mean, arrogant Maan doesn't only deserve a slap. More that that, it wouldn't be enough to make him realize his mistake.
I think along the slap Geet should return him back the ring and the taveez- as she had them with her- and say "now our relation had completely finished" from then on she should be completely indiferent to him, only then Maan would realize his mistake and would regret it.
What do you think guys?