Answers
How to stop caring what people think
Short answer: stop caring what the wrong people think. Make a short list of opinions that genuinely count; almost no one is on it. Build a full enough life that the rest becomes bandwidth-expensive.
How do you actually stop caring what people think?
You don't, fully — caring what people think is a social instinct that kept your ancestors alive. The goal is narrower: stop caring what the wrong people think. Make a short list of people whose opinion you'd genuinely take seriously, and notice that almost no one on the internet (or in the back of your head) is on it.
Why does it hit so hard at 1am?
Because at 1am your prefrontal cortex is offline and you're running on threat-detection. The thought that someone might be judging you feels like real data. It isn't. Almost every 1am worry collapses by 11am the next day; act accordingly and don't make decisions in that window.
How do I post / speak up / wear what I want without spiralling?
Decide before you post that the outcome you want is the act, not the reaction. You did the thing. The likes, comments, and silence afterwards are data about other people, not about you. The spiral only starts when your self-worth is tied to the response.
What's the long version of caring less?
Build a life full enough that other people's opinions become bandwidth-expensive. When you have your own work, your own people, your own quiet rituals, a stranger's read of you stops being free real estate in your head — there's just no room.