I accidentally clicked the wrong button because I wasn't paying attention, and messed up my storyline!!! How can I fix it? Is it even possible? I think I'm genuinely having an anxiety attack over this, lmao

It might be easier to help if you explained exactly where you are in the story and what choice you clicked, if you remember. There is a full story walkthrough (warning: image-heavy and contains spoilers for later content) that you can consult too, if you want.

If it helps, though, I'm pretty sure there's not anything you can do in this game to totally mess up the story...? Like, everything more or less ends up in the same place eventually, iirc. Sylestia isn't a game with a lot of branching paths or anything like that. So you probably don't need to worry about it too much ^^ (though I understand that can be easier said than done)

There is a total of one event in the entire storyline that has any lasting ramification, and it doesn't actually affect the continuing story, just which of two NPCs you have at Esior's Haven's barracks (and that difference amounts to which NPC image/text it uses, not the functions.)

Overall, the only differences between options is basically just what text you get for every other 'pick a or b' instance in the game.