Anger

I have done something wrong my whole life, Ive bottled up my emotions. Ive never gotten mad, Ive let people walk all over me. they've hit me, insulted me and i never got mad. Ive never used my anger. So it builds up and builds up over time. It got out of control, now there is overwhelming anger in my head. No happiness,No love, just sadness. It has taken over my mind. I have to over come this overwhelming anger, but how?