You shouldn't feel like a freak, this can be due to something or combination of things.
It may be a good idea to take this up with your pdoc and/or therapist.
This is not necessarily limited to Bipolar mania,not all types (and there are several types/levels) of Bipolar disorder(s) experience severe anger and/or violent behaviour. Unfortunately,narrow minded people have stereotyped what Bipolar disorder is like, creating another stigma on those dealing with mental disorders.
In fact,your anger may coming from some form of a personality trait,influence of environment one lives in,physical disorders,hormone imbalances,medications,life situations,etc. A therapist may be able to help you pin point what is behind this, and then suggest techniques and/or treatment to help get through this.
I personally wouldn't wait long on this, the sooner you seek professional help, the sooner you can start working on this as well as prevent the chance of you losing it and having a confrentation (sp?) with someone.
I wish you luck with this, and feel free to keep us updated if you so wish.
Please take care,
DE