The worst comment I ever got was just someone complains about how short my update was (On webtoon), and I replied to them in the nicest manner as usual explain in detail why I can't make my update longer. I don't know what happened but they deleted their comment shortly after I replied to them. Then a few other people popped up in the comment saying they understand why the updates are short and they were grateful just getting to read the story weekly for free.
So there is my experience. As for some trolling comment like "Kill yourself you suck" or something along that line... omg children go back to your mom's basement. I have no tolerance for these kind of people and would often just turn a blind eye on them. I'm sure if my readers saw these kind of comment, they would be out for that person right in the comment section. LMFAO I saw it happened so many time before. personally I would chase any troll out of the page of my favorite author so there is that
For criticism that uses heavy language and "bad", I will read through it carefully and reply back to them, thanking them for the criticism and move on. I do get affected by "mean" criticism, but I forget about it really quick. Maybe talk it out with your friends who understand you, just having them listen to your rank surely will make you feel better.