I can be insensitive sometimes

I learned today that I can be very insensitive. I know that for a while, I'm trying to work on it, but I still fail sometimes. I have flaws. Many. I commented somewhere and provoked anger. But what hurts me most, is the disappointment I caused to one of my friends. I was asked: Why? Why did you write this in the first place? The answer is: I don't know. :( Sometimes my actions just don't make sense, sometimes I just don't think. Sometimes I'm self-centred in a bad way. I'm learning a lot recetly, but sadly, it's because I'm making mistakes. I have to learn by not making mistakes, but by being careful and thoughtful. I need to find a better way to express myself. Words sting, opinions hurt. Not everybody is always laid back on every issue. I know, because I'm not, too. So it doesn't matter what my intentions were or if I felt that my words are harmless. I should've known better. I hurt a friend, and I'm sorry.