I'm generally a mild-mannered person and I have to act as an angry character. What should I do?

I can only remember getting mad three times in at least the past four or five years, so being angry is not something I'm used to. I'm part of a drama team, and in one of our skits I have found out that my girlfriend has given me AIDS and has been stealing from me and I'm supposed to blow up, get angry, and leave her. How should I act, including voice inflections, attitudes, reactions, and body movement? And note, if you point game on my question I'm reporting it, because I actually need help, not spam.