I would just tell her that YES you are upset with her. Not mad but upset. She is supposed to be your friend... it does not mean that she owns you.... it does not mean that you can be her punching bag whenever she is not happy... you are allowed to be friends with other people or have other people be near you. Just tell her that you feel perhaps you should not be friends anymore until she can prove that she can be a FRIEND.... until she can be civil with you and others around you. You do not need that kind of treatment, attitude or drama. Tell her you are more than willing to be friends with her if she can start treating you like a human being and a friend.