Being triggered by other people's emotions is real and it's hard to distinguish sometimes between your own emotions and someone else's.
We don't want someone else telling us that our emotions are wrong or not real, so why would anyone else want us to say or think the same thing about their feelings, especially anger.
I don't do well around anger or confrontation, for most of my life I've avoided it all costs. When those around me would get angry, I'd walk away or not want to be a part of the conversation. I would tell them to calm down, or relax, or say "I don't know why you're so upset, just think a different thought." By doing this I was showing them that their feelings weren't validated.
Then when it overtly happened to me, I started to see something different. I had to look within myself and do a lot of work around allowing others to feel their emotions, while also keeping mine in check.
Here is my experience and how I recently started to see that the work I've done is paying off.