A break

OK, so I had a mini-meltdown in my second 8th grade French class today. I have to say that overall, I can literally go days and days without having a single issue in my room. Honestly. It's set up so that they're (hopefully/ideally) motivated to speak French and not English, and having to listen to me in French makes it pretty necessary for them to pay attention. 8th graders get a little squirrely because it's right before lunch (and I can hear their stomachs growling-literally) and then right after lunch-but mostly-I can go days without having an issue.
Today I was tired. And crabby (read:hormonal and having lots and lots of morning sickness), but I was hanging in there. My morning went really well. 6th graders are studying he is/she is and adjectives, 7th grades looked at photos of past trips to France to talk to them a little of what it's like there, and 8th graders are learning the ever important verb "to be." I decided that they would be excited, so we'd try a game of pictionary, but with a twist. So one team draws, but any person in the room can stand up if they think they know it. I call on whoever and they have a chance. More people involved. Plus they were drawing entire sentences, like "They are listening to the radio."
1st class was fabulous.
2nd class just started off really criticizing each other. All I could hear was their tone. "Whyyy did you draw thaaaaat? That doesn't even look like blahblah".
I asked them to speak English. I asked them a few times. Then I just lost it!
I didn't yell, but I was like, "I need you guys to STOP criticizing each other. Seriously! Why do you feel the need? Do you think you could do better?"
Sort of lecturing.
They totally just stared at me because this is not typical Madame behavior. But I had just had it!
Times like this make me reflect . OK, now that it's over, what could I have done different/better?
I've thought about it, and I know I could've been calmer and had more of a discussion as a class, asked some questions-but there is a part of me that says sometimes it's ok for me to really tell them what I think. Not yell or be rude, obviously, but say, "Hey! What you're doing is not ok!"

Ugh. I'm very glad it's break :) I could use a few days off.