Sibling Fighting

I'm about to strangle my teenagers today. They have been fighting over some stupid thing, and plotting revenge. So far they have stopped short of physical violence, I think because I threatened them within an inch of their lives if they hurt each other. Something happens to me when my kids fight. The adrenaline kicks in, and I become something superhuman. I think I have always been this way. Even as a child, if bullies picked on smaller kids, I became enraged and went in to protection mode. But I especially won't tolerate fighting among my kids. Usually if they start to physically fight, I use a well placed pinch to "guide" them to another room. I think what really gives me strength is that my kids rarely see me that mad, so they know they better knock it off because they aren't sure how mad I will get. Usually I can threaten them with doing chores, or grounding them from privileges, and that seems to help, but for some reason that wasn't doing the trick today. The worst part is, I know something is still brewing.....