Agree with you. RK reacted in this manner as he is in shock. He doesn't have problem with Madhu taking revenge as much as he has with Sultan being privy to all of Madhu's plans.
RK needs a bit of time to overcome this shock. He wasn't angry at Madhu nor was he shouting. All he was asking for was an explanation which Madhu wasn't capable of giving. RK asked simple questions, one of which was, what was Sultan doing in their bedroom just a few hours before the wedding with Madhu?
Had Madhu given satisfactory answers, RK's reaction would have been different and he would have been bashing Dipali and Sikky at the moment for their interference.