In halakha, you have to take care of other person’s sensitivity. You usually can’t say – I did not mean anything bad, it is he who is too sensitive. Online discussions have several extra challenges:
1) you don’t see the person and he does not see you. This also shows in emails between people who know each other. Usually, it is better to pick up the phone than to continue angry emails
2) you don’t know the person and he does not know you, so you make worst assumptions. This is similar also to books, but
3) this is written quickly and 4) we are not authorities that can claim respect l’hathila so many people do not apply l’tzad schut
general advice – if there is misunderstanding, it is not a big deal, both sides should adjust how theu read/write to make it into exchange of ideas rather than a meaningless flame war. If you are not improving in either writing or reading experience, time for self-review and ask someone else to give you an advice.
Hopefully, you’ll develop an ability to express yourself better and to read with more understanding/