Good to read your journal and see you doing well. Hopefully i can work on my recovery the way you are doing .
About that negative thing about the car guy , it happens with everyone . Even i sometimes get irritated on certain things and stay mad at them for hours . And yes its difficult to let go of that negativity.
But I would like to share one of the things i have learnt to let go of negativity and stay happier most of the times. Most of the time our mind is occupied about something that happened in the past or something which might happen in the future.
Yes sometimes those past/future thoughts can be good like fond memories or expectations about something bright in the future. But most of the times past/future thoughts bring pain , sadness and all unwanted feelings of negativity.
So one should always try to live in the present , more specifically present moment. Like in your case you were a you were angry at a thing from your past (not exactly past but it was not the exact present moment either ). If you could try and focus more on your present moment then perhaps you would not have felt that anger for long.
I must say you did well though and got out of that feeling quickly. But i would suggest you to try and practice the habit of living in present moment as it will truly help you to enjoy the beauty of the present moment one is living in
Hope you would find it useful