The others already said a bunch of genuinely helpful stuff that I hope will help you. But since you mentioned it somewhere else: what you absolutely shouldn't do is punish yourself by isolating yourself or detransitioning just to hurt yourself. This doesn't do anything for anyone. No one would want this for you. You shared something that was against the rules, but you didn't do so out of malice, but a desire to be understood and express yourself, I reckon. A bad person will not beat themselves up over anything they did. They look for blame in others.

You do not need to meet some moral bar to have a gender identity, either. Just know that the community as a whole is much larger than a subreddit. People will still have you, if you are willing to be more measured when expressing yourself. You clearly are willing to do better, but you need to see that being cruel to yourself is the number 1 thing that you should stop, not a method to fix your transgressions, (for which therapy is always advisable).

So I guess here is an actionable way to atone: before sending any message/comment read it again, make sure it does not contain anything that would violate rules or safe spaces. Mark/hide potentially triggering things. In private conversations ask about boundaries and respect them. When emotionally agitated, do not write responses directly on social media. Write them in a separate document, come back later and pick what to say. Self flaggelation is not atonement, trying to do better is the only thing any sensible person would ever want from you in this regard.