Do you ever try any grounding techniques?
There's one called 5-4-3-2-1
You can do it anywhere.
Wherever you are: name 5 things you see in the room
4 things you can feel
3 things you can hear
2 things you can smell
and name 1 good thing about yourself.

Sometimes it helps to take you out of your head for a couple minutes and at the end of the exercise, you will have calmed down at least a little bit.

Otherwise distract.
Sometimes writing about the moment when you're too caught up in it only makes things worse because it amplifies when you give it too much thought.
Self-soothing also helps me a ton when I get too upset.