I did the same two weeks ago. It took me a whole week and a half to get up the courage to give my mom the note, and I was a nervous wreck for a whole day, while I waited for her reaction.
It went great! even though I was sure she'd react negatively, she said she didn't understand it, but she loves me.
I'm so much happier now that I have my family supporting me, I had my first therapist meeting on friday!
Good luck to you, I'm sure your family will love you no matter who you are. Just be sure to try to explain, if they have questions, and be patient as some family members may take longer than others to accept you (same happened to me with my brother, he still doesn't accept it. but I'm sure eventually it'll pass)