It isn't helpful to hold your feelings in and suppress them. Get rid of your anger, irritability, or sadness by putting it on paper and expressing yourself.
You can write poetry.
You can write a journal entry.
You can paint or draw a picture.
It is important that you don't hide from your feelings. You don't have to be ashamed for feeling the way you do. It isn't your fault that people have treated you badly, or that you're genetically predisposed to mental illness, or that you've been unlucky recently, or that you're naturally antisocial.
It is a lot better to express your negative feelings that it is to sit there and suffer as your mind just builds the anger, irritability, and sadness inside of you.
You can express yourself at http://www.depressiondodging.com/expressionTherapy.html
You can learn of more ways to get rid negative emotions at www.depressiondodging.com