Hi AnxiousGirl,
You must have had someone/people in your life who reacted badly to your 'vulnerability', or perhaps you witnessed someone else getting hurt when sharing their inner world and thought you'd never risk the same thing happening to you.. I'm really sorry it has had to be this way
The thing is, what you shared with your therapist wouldn't even be considered 'vulnerable' had there not been an incident/experiences in your past that convinced your mind that it is dangerous to share your inner feelings and thoughts. It'd just be you sharing who you are with the world!
My advice would be to tell your therapist what you've told us here - how uncomfortable you've felt after sending her the email and what you fear would happen next. I'm guessing this will tell her more about you than what you actually wrote in the email or have shared with her in person. I'd go so far as to say it'll give her a lot of insight into why you sought her help in the first place.
Also, I don't think she will, but IF she were to react badly to what you shared with her, just know that in that case, she's out of line and you deserve to find yourself another T. Whatever happens, I'd urge you not to give up on therapy just yet - you deserve to become FreeGirl instead of AnxiousGirl, and proper therapy will help you there! Good luck, and let us know how your appointment went