Finding the thought in the trigger

I have a question about when I feel “triggered” by something someone says. For example, a receptionist was annoyed at my children the other day and I reacted by getting immediately angry at her. I was trying to figure out the thought that caused the triggered but it feels like it happened so quickly, I couldn’t recall the thought. I was just angry. When I think about it I think a string of thoughts about her and myself… and of course none of them are positive. Thoughts like, “she hates children” “are my children really that awful?” “Why am I so angry” “why is this still bothering me” “I don’t want to have to ever see her again.” “Maybe I can get my follow up x-ray at a different hospital” and madness happens in my head. I’m not even sure where to start modeling this, but it happened yesterday and I’m still upset and I don’t want to be upset, how do I start to change these thoughts and get my brain back?