I agree that you need to leave this T, but I also get your concerns about the letter. Could you maybe take a break from her while you check out other T's, with the option to come back in August if you can't seem to get a T who will write you a letter? Or...is it possible she could just write the letter for you now, then you can go find another T? (Or does it have to be a T who's treating you at the time you have the surgery?)