First, thanks for your bravery in telling us! I know it can be very difficult, even if we don't know you in person.
I am a lesbian. Yet I was once married to a man, and together we had a wonderful daughter. I was already into my therapy for over 20 years, before I told my T that I had fallen in love with another woman. She didn't bat an eye. I think she has always been more concerned that I am in healthy relationships, rather than who I was with in them.
I think you might be surprised at how many of "us" there are. But what's the worst thing that might happen if you revealed your secret to your T? Sometimes the anxiety about telling can be worse than the actual telling.