What is a good way to deal with frustration and becoming angry with your friends?

One of the ways to handle this kind of situation is to express your anger and frustration by yourself first, on a pillow for example and really let it all out, several times a day is necessary until you feel clearer in yourself and can express it more clearly to them. You would then be able to explain how you feel without the emotional charge which brings confusion for you as to what to do.