So today I brought my mom with me to my therapist appointment and came out to her that way. I was really nervous and embarrassed and afraid to do it, but I decided that I needed to, and if I didn't just get it over with I'd keep putting it off and putting it off.
Anyway, it went great! She took it really well, and said that she wasn't actually surprised! She then proceeded to talk about how she's kind of always wondered. Pretty much that session consisted of her asking questions and talking to my therapist. When the subject of HRT came up she actually asked her how she could get a doctor to prescribe them to me, if I decided I wanted them. She also said she thinks my step-dad would be fine with it, and that she won't tell anybody if I don't want her to. The best part, of course, was that she said that she just wanted me to be happy and that she loved me no matter what. I couldn't have asked for a better reaction. My mom is awesome and I love her.

I'm so psyched about this. No more "Why are you seeing a therapist?" "Uh.... because...?" I'm finally moving forward, and it feels good!