I have similar problems, but whenever I get upset or angry at anyone I imagine myself stabbing them to death through the heart or under the chin, through the brain and out through the top of their head. I know it's wrong and hope it never happens.
I used to loose control of myself and tried to smother my younger sister with a pillow, but after a while I realised what I was doing and removed the pillow. She got up and went out of the room before she passed out. Nothing has been said about it since.
Another time when I was at school, I was out playing with a friend and while he was climbing over a school gate I started shaking the gate vigorously. I don't know why, but I was trying to impale him on the spikes.
Hopefully you will not be in the same situation. If I were you, I would seek help from a doctor. He will be able to help and give you guidance, before you go and see him make notes on yourself, ie. what triggered the anger, how you felt, what you did and what you think you might do. Are you under any stress at the moment if so make a note of it and tell your doctor.
I hope this helps, it'll save you living your life hating yourself for what you did at an early age.
LOL just looked at the date for the op, sorry