The first hurdle when emotions are involved is to realize it. Quite often, we recognize it afterward. It is often too late when violent words show up, heads heat up, and lizard brains take over.
I by no mean claim I have mastered this skill, but in the past, I have used two tricks to train myself in this regard, and it might help you as well.
The first trick I used was to practice meditation.
There are a lot of benefits to meditating. The one that helped me the most was to recognize when my brain is drifting its focus somewhere else. Brains are thinking machines. Thus it is precisely their job to associate ideas and jump from one to the other. However, what is helpful is to be conscious that this change is happening and decide to let it continue or rein it down.
I am sure you have experienced this already: your brain takes you on a tangent that is so fascinating that when you snap out of it a few long seconds later, you realize the world has been waiting for you to say something, and you have no clue what.
I can realize earlier when my brain is drifting away from a discussion or when some emotions are taking over. Meditation helped me realize this sooner. I have the feeling that this skill transferred into my daily life.
Another exercise I like to practice is naming emotions. You can refer to this blog post I wrote a few months ago called "The vocabulary of emotions" and use the "feeling wheel" to explore the emotions you detect. As a non-English native speaker, it is exciting, and my first realization was that I was missing a lot of vocabulary.
The wheel describes ever more precise ways to label our emotions. At the highest level, we have basic feelings: surprised, bad, fearful, angry, disgusted, sad, and happy. But you can drill down each of those basic emotions into more granular ones. And those can, in turn, again be drilled down into more precise feelings.
For example, if you detect some kind of sadness in your voice, you can wonder if it is loneliness, vulnerability, despair, guilt, depression, or hurt that you are feeling. And if you recognize that this sadness comes from a feeling of loneliness, you can wonder if it is more because of isolation or abandonment?
I believe that putting words on things helps make sense of what is happening. In time, being used to labeling emotions enables recognizing them earlier.
What are your tricks when emotions threaten to take over?