It seems so simple, doesn't it? Have you heard it a thousand times?
“Just take a breath!”
From one of Thich Nhat Hanh's books (either Anger or Creating True Peace ) I gleaned the idea of “Breathing Room” or a “Breathing Space.” We incorporated it into our home and life: a dedicated space where there's a Mindfulness Bell that anybody can ring at any time, encouraging everybody in the house to Stop. We meet together in the Breathing Room. For every time the bell rings, we all take three deep, slow breaths.
Tension often dissolves instantly. It's astounding what a Return to Awareness can do to discharge the negative energy of a situation. I won't guarantee that's all you'll need to do, but don't worry. We've got lots of tools in our Communication Toolkit!
It may be wise (as well as comforting) to start any conversation with Breathing. A dear friend and I connect weekly on the phone. She also practices mindfulness and we often begin our phone conversations with 3-5 minutes of quietly breathing together. This is a useful technique as a practice that you can generate in relationship when there's not conflict. That way when a conflict arises, the practice is familiar to both of you.