I mean, first of all remember that it is a dumb internet community, and especially the ones like you describe tend to be populated by shut in neckbeards. You, meanwhile, have shit to do that is more important. Go do that shit.

If it is really invasive, then stop thinking about it and start feeling it. That is, don’t try to logic the feeling of how it was unfair, or they are assholes, or you’ve been mistreated. Instead focus on the sensations of the emotion you are feeling. You are feeling angry? How do you know you are feeling angry? A tightness of facial muscles? The hairs standing up on the back of your neck? Thoughts of violence or revenge? Notice the feeling with curiousity for a breath or two, or a minute or two if you still have time, or until the feeling passes and your mind wanders to something else.