Heart vs. Head

My heart always has control over my head. Ever since I was little I have been a very emotional person. This has led me to be extremely empathetic and one of those friends that would do anything for you. It has also led me to be a person that people walk all over. I understand we don't live in Utopia, but it is still hard sometimes to understand why people feel the need to hurt others in order to make themselves feel better. I am not perfect and will admit I have hurt other before in an attempt to make myself feel bigger, but in the end all it did was make me feel like a lesser person. This is not the case with everyone obviously.... I don't understand how people can act one way and then turn right around and do something that clearly contradicts their previous actions. Is it that people are so out of touch with their true intentions? Or is it that some people just truly don't care how their actions or words affect others and are only interested in their own satisfaction?