(((((((Shoez))))))

I believe you! I know what it was/is like to have parents who act one way around everyone else and act a different way in private. I'm sure this is not a new scenario for your T to face. Your T may just want to see if there is any likelihood that your mom might protect you in the future. And if not, help her decide what to do to best protect you. I also think you should talk about your fears about this session before your mom comes in, but your T probably wants to decide what her actions should be as soon as possible and hence why she wants to see your mom so soon. I know when I was a teenager I was faced with a similar situation and refused to let my mom come to session (though it was only a light suggestion on the part of my t). I was afraid that my T would believe that my mom was all nice and not believe what I was saying. So I have been there.

Take care of yourself.