You need to find a way to properly vent your anger (and believe me I've had a lot of experience with this)... but you need to find a way to do it safely. People always say "hit a pillow" which is just stupid, it doesn't do anything. Hitting things (as you found out...) can release anger, but usually it has to be something that will hurt you, like a wall (I don't recommend this, you get used to pain quickly but it's just stupid). The best way to vent your anger is by screaming. Sure, you look like a total nutter, but walk somewhere isolated, or turn music on really loudly... whatever, just concentrate all your anger into a scream and let it out. It sounds absolutely stupid, I know, but trust me it works.
But yeah it's worth seeing someone about your anger if you can... a counsellor if you can't find anyone else.