Thanks for the welcome!

For some reason I have a hard time talking, not only to her, but to anyone. We've talked about this, and other things that have been helpful, but I feel like I am stuck.
What I really 'want' to tell her, is the relationship I am having with my best friend (a female) that has grown into something more. It is hard to explain. My mom has confronted me angrily about it and I am very confused and sometimes ashamed. It is a horrible feeling pretending I don't something that I actually do. (I hope this makes sense). I feel like I will never be able to tell her, or anyone because I am so scared of being judged. Week after week, I think I am ready, but I keep putting it off, making it harder to talk about other things during the session.
I always tell my therapist that I am terrified before each session and she asks me 'what are you scared of', but I always have a hard time answering this question.