Long post sorry, I had something similar happen to me.

Everyone here is spot on in that this guy was an asshat. There are others saying you are giving this too much thought or weight and that you should be able to stop doing that at any given time.

That’s true, but not easy, otherwise you wouldn’t be asking how to stop thinking about it. The key to stop giving shit like this so much weight lies in figuring out why it bothers you so much, and don’t just answer “because he was rude”, instead look at what attitudes/ thoughts/beliefs you have that are making you feel bad about it.

Once when I was 18 I started working at a very prestigious place in a sort of apprenticeship trial thing. I was left completely unsupervised, not given any deadlines, not told how to do things, and although I did a really good job, I was too slow and the manager wasn’t happy about it. Instead of just saying to me that he needed someone working at a different pace and just tell me to find work elsewhere, he scolded me, gave me a really patronising speech about how maybe I wasn’t cut out for the job and that perhaps I should consider finding happiness through motherhood since I’m a woman. Not even kidding, he was that much of a piece of trash. And of course I was fired.

So that particular episode really haunted me for years until one day I realised I was working in that very same field, doing a really good job elsewhere, and that the only reason he was that rude was just cruelty, nothing wrong with me. It was something obvious to me from the very beginning, but it took my subconscious or whatever a good 6-8 years to fully believe what I already knew.

Now it’s your turn, you’ve done the first part which is becoming aware of it, what’s left is believing it. Good luck.