how should you deal with a situation online

where you think someone's got a false perception of you and sees you in a way that isn't based in 'truth' just by what they're posting and the words they're using in their comments to you? - i've been in that situation quite a few times over the years and it usually causes me to feel really angry, verging on becoming aggressive with that person.

what's a good way to respond to that situation with someone you're interacting with online?