Everyone gets angry sometimes; that's natural. How people react to their anger is an interesting study in character. Some people erupt, venting everywhere -- and then the explosion is over as quickly as it began.
Then there are those who sit on their anger, who let it build and build rather than expressing it immediately and directly. Even when the dam bursts, some people implode rather than explode. Sound familiar? That type would be you. Whether it was societal pressure or family history, somewhere along the line you learned that you shouldn't express your anger openly. You either turn it inward on yourself, which can lead to depression or other health problems, or you shift into passive-aggressive mode. That way, at least there's an outlet for your anger, murky as it might be. As you mature, there are certain steps you can take to maximize the positive attributes of this placement. First of all, recognize that you are thin-skinned. If you find yourself getting offended easily, try to be a little less sensitive and don't take everything so personally, or so seriously. When you feel angry, find a way to express it clearly and directly, to the appropriate person. If writing is more comfortable than speaking, take that route. Keep a regular exercise routine, near water if you can.