The HeartMath Institute teaches us about three things which are not always so easy to practice in difficult or tense situations, but which, with practice, will bring meaningful results:
Appreciation: Most likely, no matter how bad things feel right now, you have a lot to be appreciative for, even as it’s directly related to the person or problem who is angering you.
Non-judgement: If you can manage to pause judgement for a moment, it can change everything. Note that this does not mean you have to agree.
Forgiveness: Both for them, and for you. Unconditionally. (If it comes with conditions, it’s not forgiveness.)
I’m willing to bet that during most situations you’ve been in which have gone emotionally awry, one or more of these “Heart Power Tools” [credit again to HeartMath for the phrase] was absent.