I'm glad you were able to tell your mom, and that she was supportive! That's SO awesome!!
I hope you will be able to tell your T also. It may take a few false-starts (it did for me), but hopefully you can reach that point.
Another thing I thought of that had helped me in the past: I left a message for T on her voicemail saying I needed her help in talking about something really important next session. I told her it was really difficult to talk about, but that I didn't want her to "let me chicken out" over it. I vaguely mentioned what it was about, and asked that she push the topic. It was really helpful to have her know that I would be nervous talking about it, but that I wanted her to keep on the issue. When I panicked in session, she reminded me that it was ok to feel nervous about it, and that she would help me talk about it, but that I had asked her not to let me back out. Just hearing again from her that it was ok to talk about, and having her know that it was something I needed her to keep on me about made it easier to talk. Dunno if something like that would help, but I thought I'd mention it anyway.
Good luck next session.