I caused psychological trauma for a guy for no reason.
Do you regret causing this guy psychological trauma?
I do, I regret making him lose his temper
Emotionally harming and abusing someone is cruel and can be quite harmful. Moving forward you should treat others with the kindness of respect they deserve.
I don't feel good about the way I treated him. I'll try to stop harming people.
It's mature of you to not only acknowledge your faults, but to feel regret over them and seek change. Now that you know how you feel after such behavior, I'm sure you'll do better!