How do you personally restrain from responding to someone online because of an insulting or ignorant comment?

i like to ask controversial questions about sensitive issues so naturally things get heated. i am not a politically correct person & admittedly need to use more tact sometimes. i find it challenging sometimes. mostly when people misunderstand what i was saying or accuse me of something. so how do you keep from responding to an insulting or ignorant comment that gets under your skin?