The saying goes that you always hurt the ones you love, and it's true. The reason is because 1) you wouldn't dream of being insulting to a total stranger, unless circumstances warranted it, like they were yelling at your kid or something, and 2) people that don't love you back don't care enough to be hurt by your dumb a__ness. Rolls off their backs. So, we have the problem of caring about someone but at times lashing out at them and causing them pain. Why would we want to do that? It doesn't make sense.
Satan loves a good fight. Just realize that when you want to say something hurtful. Ask yourself where are those thoughts and words coming from? Not from a prompting of the Spirit, I'm sure. Patience is of the Lord, and we are encouraged to develop it. It's hard not to get angry and say something mean, and sometimes it's harder to keep from saying something meaner back. Still, I hope we all (me especially) learn to be more thoughtful of others, and realize that a soft answer turneth away wrath. We should be building each other up, not tearing each other down. Let go of the grudges, if you have any. Life's too short to waste. Nuff said.