Umm. go on Twitter and shout out my frustrations to the universe?
Okay, more seriously. I'd call a friend whose judgment I trusted and vent. I would chose someone who won't judge me if I'm being unreasonable. Unfortunately,I get pretty upset, even when my kid is not suspended. So I know who to call. I hate doing it, of course, because I don't really want people to find out how mad I can get, but on the other hand, it's safer and more effective than telling the kids things that I will have to appologize for.. Later, when the whole thing has calmed down, I thank the friend and I also try to make sure I call again when things are okay, not just in an emergency.
There are times when you can't get anyone on the phone. In that case, I'd tell the kids that I'm having a problem coping and being reasonable at this time and go hide in my room for a few minutes until I calm down.