What would you do?

Sorry this is so long.

Flash Forward: yesterday his speech was hilarious. He said a couple of funny things about how weird the school was. Everyone laughed. The faculty laughed. I was sitting in the grass on the hill next to the ceremony because tickets for seats were limited. Our younger sister and my 4 month old baby we with me. We got there 90 minutes early to steak out seats so everyone around us was aware they were choosing a seat near a very tiny baby. A group of 5 kids who had graduated the year before decided to sit behind us. They talked through the majority of the ceremony, mostly making fun of people's outfits, how they wore their caps, how 'angsty' different graduates looked. Then came my brothers speech. They hated it, they made fun of him, they didn't understand his humor, they said he was disrespectful and questioned why he even chose to go to school there. I managed to control myself. Then diplomas started. They knew about 40 kids who were graduating. They screamed for each one of them. In my ear. Making my son cry. One even said 'oh we mad the baby cry! Oh well, my friends are graduating' and went back to screaming. I waited calmly until the ceremony ended. And then I stood up and said 'hi I just wanted to introduce myself, I'm Zack's sister. His speech was hilarious, you all have no sense of humor, when he's on Saturday night live one day, you all will be living in your parents basement. Oh and by the way, thank you for screaming in my ear the entire time and making my baby cry, you could have sat anywhere. You talked shit about people the entire ceremony and are all terrible people, your parents must be so proud. Your behavior was disgusting you should all be ashamed.' Dropped the mic picked up my son and walked away.

They all stood there in shock, said nothing. Then, after I caught up with my brother and told him what happened one of the little jerks came up and tried to tell him how he loved the speech and I misunderstood. My brother said 'no you didn't but thanks, have a good life see ya never!' 

So my question is, how would you have handled this? Did I go overboard in my blackout rage? Should I have throat punched one of them? Whipped out a boob and sprayed breast milk at them? Or did I do the right thing?