Why do I feel so much hatred inside?

You need professional help.

You might be in a manic rage. In most people the mood swings of Bi-Polar disorder range from deep depression to a state of giddy, carefree extravagance in which people indulge in lots of sex, drugs, gambling, etc. They spend too much money, lose a sense of proper boundaries, etc. But others, like me, flip from despair into rage, rages that last for months. During these rages I break things around me, scream at minor irritations, scream at people on the phone, have no patience for anything that frustrates me, and in general entertain fantasies of killing half the people in the country. I lock myself in my room when these rages occur, and now take lithium, which helps a lot.

Don't let bad moods control your life. Life is more than your moods. If you're too young to go into therapy by yourself, find ways to control your moods. Isolating (something else depressed people do) is not helpful. You need to get out of the house and hang out with friends.

Frustration & anger, depressed passivity, and anxiety. At its worst, I would take out hateful emotions mainly on my self, but occasionally 'just' be psychologically mean to those whom I most cared for.

In any case, connecting with a psychologist was greatly helpful. That said, many people are (understandably) reluctant to make a single appointment. That's the hardest part.

What you really need is a good old fashion spanking.