What I have found out from not only personal experience but from other girls out there in the world, is that people do not know what to say when us, (woman) are agitated. After talking with plenty of diverse woman I found multiple patterns that have been reoccurring. To help all the other people out there who are struggling in the department or you just simply can relate; here's a list to not only save you the headache but save us ladies one as well.
Do NOT tell her to calm down.
We know we need to calm down. Just do not tell us to do so. This will just awake the inner beast.
"Shh.."
First of all, no one likes a shh-er. For you to even do this to others is rude. Second, do this to a girl when she's angry? Ha! That's like dancing with the devil.
When she says, "I don't want to talk about it." DROP. IT.
If you keep asking her, she will explode. Having her complain about you not continuously asking her is a lot better than bugging her. She will tell you eventually tell you. Let the pot simmer.
Don't tell her how to handle something.
Just don't do it. Avoid this at all costs.
If you're caught in a lie, do not deny it.
Face the truth, and stop digging yourself into a bigger whole and start apologizing.
Do not blame it on her period.
Whether it is because of our womanly time of the month, whatever you do. Never blame it on that. Things will escalate to a whole new level.
Avoid any rude name calling.
She will turn into whatever you called her.. you will regret it.
Never say the phrase, "You're just like your _____."
They will loose whatever their train of thought was and will either provide you with a comeback are lose their minds. Just don't.
I can't help you get out of the situation or how to avoid it but I can help you avoid making things worse. Take this advice, run with it. You'll be surprised how well things go when certain comments are avoided.