I am definitely not completely mentally stable, but I get this. Most of my anxiety is definitely social anxiety. I ""solved"" this by doing two things: 1) doing something about it when I can, and 2) realizing that not everyone's thinking about me.

On the first thing, I can give an example. The other week, I went out with new people I met. Towards the end of the day, I accidentally made someone upset. Afterwards, when we were all back home, I sent a text to the person apologizing clearly and honestly (it was just a misunderstanding, so I cleared it up). Me a few years ago would've done nothing, thought about how much I fucked up, and lost a potential friend for good because I was so worked up over something so insignificant. They seemed to really appreciate the text, and the next time I saw them, everything was great as usual.

But sometimes there's nothing you can do about it. A small example of this is the other day, when someone said hi to me, and I kinda just ignored them lol. Anyway, this made me anxious: what if they hate me now, what if they think I'm rude, what if they never wanna talk to me again? Classic overreacting. I'm not sending a long apology over not saying hi back to someone I've never even texted one-on-one before. So what do I do? Just put it behind me and just do it right the next time. And that's what I did.

That second example kinda ties into the second point: you are not the main character. Most people do not think about you. This is something I really had to drill into my own head. What helped me was thinking about when nice or neutral people ever did something a little rude or mean one time. For the vast majority of people, I literally cannot remember when/if that happened. Obviously this changes if the person is constantly rude/mean to me, but most people aren't. Most people are chill. If you accidentally didn't wave to someone, or you bumped into someone cause you weren't paying attention, or whatever, it is very, very likely they forgot about it by their next meal.