Josh, I can relate. I was SO terrified of coming out. I had my whole life planed out: I was going to go FAR away to university, and I would come out there and I would never see my family ever again. It was a good plan.
Except, I wouldn't wait that long. I ended up wanting to die (not suicidally) if I had to play a girl one more time. So I came out to a few relatives. It was not the best, but it wasn't the worst either. And I just got tired of pretending, so I finally decided that I don't care if they all hate me. So I came out to EVERYONE. I'm out to everyone who I care enough to tell. And it was AMAZING.
My family really surprised me. They're all either okay with it or won't say anything if they're not, lol. And people at school have been just amazing about it. Coming out was the best thing I ever did. I don't have to run away to university anymore. I can start transitioning now.
So, I just wanted to say, people might surprise you. It might not be as bad as you think.
And as for her thinking you like guys... I still get that, lol. Only everyone assumes I like girls since I'm trans. Truth is, I'm kinda confused about my sexual orientation, so I let them think what they want for now.