Each time you allow another person to get under your skin, you're choosing to give up control over your life. The next time you hear yourself saying "so and so makes me so mad", or "what she/he said really hurts my feelings", check within yourself to see what it is that is truly making you that upset. A lot of the times, what upsets us so much about another person is really a reflection of our own selves, things we're not aware of that we don't like about ourselves. Pay attention the next time you get upset with what someone says or does to you. Ask yourself why it is upsetting you so much. Check to see what kind of expectations you have for others. If you're expectations for other people are too high, then you're more than likely going to be going around upset all the time. People will never be able to live up to them. Just because you would not say or do such a thing does not automatically mean that others will live by the same rules you have for yourself.
No matter how upset you get about the actions or behaviors of others, it won't change anything. The only person you have control over is yourself, and if you're so busy being upset over the behavior of someone else then you have just given that person power over you. Another person cannot make you upset without your consent. Check your thoughts when this happens to see what you are focusing on.
Be careful not to get wrapped up in another person's emotions, they are responsible for what they say, feel and act. Don't allow them to drag you into their misery. Detach yourself from the drama.
Whatever it is that you feel another person is upsetting you about has more to do with you and less to do with them. Take responsibility for your emotions and get control over them. Make a commitment to yourself that you will no longer allow others to determine how you feel. As soon as you notice anger, hurt or fear arise take charge of those thoughts going through your mind, ask yourself who it is that is really in control of how you feel, is it another person that really has that kind of power over you or is it that you are letting them have that power over you? Look at the upsetting thought and tell yourself "interesting point of view that is" and simply let it flow right past you, don't hang onto it. It's not yours, it belongs to someone else.