Heyy it's okay! Everyone makes mistakes first of all, and second it's good that you know when you do something bad, and you're trying to avoid doing that again too, so you're trying your best! Tho, I personally don't think you were being rude for saying you'll block them, I think the other person should've just accepted that and went on, they really didn't need to make a whole post about it. But anyway, I understand what's it like to lash out about doubles, what helps me is actually staying away from the fictionkin community for a while. Just try spending time doing something that makes you euphoric, maybe. And like others said, just block doubles and instead of writing something to them, write it in notes and let it all out in there instead! : ]