I was a bit nervous about going to Thanksgiving, because my aunt who still wants to call me by my birth name and hasn't told her kids (so my cousins) about me is going to be there...anyway, my mom came downstairs and the conversation went something like this:
Mom: So are you coming today?
Me: Um...I don't know...I assumed I was expected to
Mom: Well, I don't want you to be uncomfortable. You don't have to feel like you have to come. If you don't, I can get some turkey and we can have a Thanksgiving dinner at home tomorrow. I've been thinking about this a lot anyway lately. Today I want to talk to her about all of this and see if we can have it resolved by Christmas. Because she really shouldn't be calling you "birth name."
Me: Well, it does look a little silly at this point to call someone who looks male by such a girly name.
Mom: That's not even the issue though, even if you looked more feminine, it's still too late in the process to pretend that you're still "her."
Me: I guess
Mom: I'm going to talk to her today, I'm going to tell her that if she doesn't want to tell her kids and start using the new name, that I will still see her and I won't abandon her, but that when it comes to family dinners, I will visit with everyone earlier in the day, and then we will have your other set of grandparents over at our house for dinner instead on Christmas.
My mommy loves me.

lol. The fact that she said "even if you looked more feminine we shouldn't call you by your old name" shows me that she's really working at understanding it.
That just goes to show you people.

Keep your head high and eventually they will have to come around, if they love you.