Picture this: You've midway through a difficult conversation or negotiation. The other person has just about pushed you to your limit, maybe with an off-hand comment or a string of subtle digs.  Your heart is racing. Adrenaline surges. Your brain calls to mind that perfect zinger. Just as the words start to leave your lips, a little voice in your head says, "Maybe don't." This comment halfway out of your mouth is almost guaranteed to take you down a path of no return. But the train has already left the station. How do you pull back and pivot without looking weak, awkward or scatter-brained? In high-stakes negotiations and difficult conversations, whether in your personal or professional life, it's easy to obsess over saying the right thing.…