Don't understand people at time!

I don't understand some people at times. Why would someone say stuff to hurt you purposely? I know that they know that they are saying things that are going to hurt, but yet they do it and don't apologize for it. They will say mean and hateful things to you and then when you get upset about what they say they get really angry and mad at you. I think its stupid that they get mad at you because you get upset over what they say. An they don't apologize and expect things to be fine and dandy. Well they need to realize that its not fine and dandy to say mean and hurtful things to you. Are they trying to shove you away and make you leave? I don't understand why they do this. I wish i knew what they are really thinking and i wish i knew what they really want. If they want you to leave then why don't they say it instead of beat around the bush.