a friend is a friend whether boy or girl.when it is ex we as a human being feel something that can only be experienced. and i think you don't have a problem.you as a person have a right to live and express your self with in the rules of the state and your personal values.
we become angry when we are hurt. right?
she responded that way because she is hurt. and may be you can understand her better than anybody else, because you were once in her place n you know your ex as a person. you can help them or close your eyes.