Madilulur incase you didnt know, verbal abuse to anyone in public can be reported to the police to take action against the person..and MORE so if its done in front of a person's family is absolutely not tolerated.

Further more if the dispute happened over a dirty glass of water, its still the fault of the restaurant to begin with and then to be rude in the manner mentioned by the OP calls for strict action to be taken against the waiter and the management.

Hope you can wrap your head around that. :)