I can see both sides of this. As a client, I would have a reaction to this because how could my therapist believe something so ignorant, but at the same time, I wouldn't want one of my clients to judge me too harshly if I was ill-informed about something like this. I agree with those who are saying to discuss this with your therapist, but I don't know that I would focus on changing her mind or anything like that. I would want to approach it from the stance that you were addressing your anxiety and how the way that she tried to alleviate your anxiety was ineffective.