Have you tried reconciliate with this person peacefully? Asking her whom she represents, why is she acting the way she is? Offer her love and acceptance? "The Gateway to Inner Self" by Robert Wagonner talks about just that - to conquer the disturbing characters with love and acceptance. It's based on the assumption, that "bad entities" are parts of ourselfs, like maybe some bad trait we have, that we for some reason don't like and thus don't want to accept as being part of us. He provides many stories, when dreamer sends love towards the "bad entity" and this entity changes into something non-threatening and in some occasions "melts" into the dreamer to form one whole character. Fighting our bad traits won't make them go away, accepting them and working on them will.