There are a lot of different learners and different ways of learning. You need to have a sit down meeting with her (whether it involves you two, or even your parents and admin). It needs to be brought up that anxiety takes over when you guys do oral assessments and how unfair it is for students that struggle with that. Instead of an oral assessment for you, perhaps a written one that you hand to her. You can even do it outside the classroom to prove that you are not stealing others thoughts and answers. This is jsut a suggestion. Goodluck my friend