friend fight, what should I do? Options

[littleswallow]

Okay, here's the deal. The Marauders (our group's name, inspired by Harry Potter) have been friends for almost 6 years, and we've never had a big fight before. There's this guy, Mike, who joined our group about 2 years ago. He and our friend Kat have a special relationship, like "more than friends but less than lovers". But we've all noticed something about Mike, like the way he shouts at us whenever he's pressured and he's kinda ordering us around. So we talked about this (without Mike and Kat) and we decided to give him one more chance (we've already been patient with him for so long) before we tell him what we observed, hoping that if we tell him, he'll try not to be so bossy anymore. But then one of our friend spilled it to Kat and Mike. And they got mad. Mike said that we were being fake and couldn't be trusted and stuff. That really irked me to the point that I almost punched him...

Anyways, what do you think should I do? I told my friends to let things cool down so that we can talk to each other without shouting. Do you think I made the right decision? We already talked to Kat about these things before but she always defended Mike because we think she loves him. But we just can't take it anymore!

Oh, and sorry about the long post!