I concluded that it's due to embedded signalling in my childhood and adolescence that I learned to suppress my anger. All teenagers at one point deal with suppressing emotions, and that usually boils down to a pivotal point where an explosion inevitably occurs.
Growing up, I was told never to raise my voice at anyone, never to lash out, never to react strongly, and to stop being so sensitive. Apparently, my coping mechanism was to shut off and try to ignore the cause if there's a risk it might get me angry. Frustration does build up though, because sometimes you're SUPPOSED to respond in anger. Alternative routes don't work, as I've discovered, and soon I find that my anger blows up at the smallest triggers. Either that, or anger seeps through in subtle aggressive and inappropriate conduct.
The trigger was that someone gave the impression that my self-expression was simply boring entertainment, especially when the primary assailant simply disappeared. That's when I lashed out. I hope you believe me when I say that I wrote a reaction entry but simply letting out my anger in writing and in private already gave me some relief. I read over what I wrote and felt content with leaving it unread. It was my sister, my only companion in all this, who insisted I make it public. My sister is the type of person who's always on the defensive. She feared for my dignity, I think, and just like she wouldn't stand someone disrespecting her then she wouldn't stand for anyone doing that to me. I just got better at tolerance, perhaps. I took her advice and of course that person responded, but I don't have the energy for the back and forth shootout. Fast forward a bit, we worked it out and apologies were exchanged and we ended things on a very good and friendly note, because she's a truthful person who just calls it as it is with no reserve (which is something I greatly admire). She's someone who recognised my writing when I came back (and just in case she's reading this now then hi :) Hope you've had a great holiday).
After that, anger came in small doses until it finally cleared. It very much started to evaporate, like how steam fades into the air over a hot cup of tea. I think. One can't escape flashbacks that are naturally enticing, but... anger doesn't dominate me.
I'm terrible at holding grudges.