Friend accidentally being transphobic

Currently I am trying to help a friend of mine figure out her sexuality, as I am her only non-straight friend. She believes to be somewhere on the bi spectrum, and while she is currently settling for that, she occasionally brings up the possibility of being pan. She has the basic knowledges of sexualities (homo/hetero/ace/bi(/pan)) but is still unsure. Usually she is awesome about being an ally, even correcting me once when I accidentally misgendered a mutual aquitence of ours (I didn't know he was trans until that moment) or helping bring up when a school survey decided the only genders there are is male and female (I stayed quiet, I am deep in the closet and so are other trans kids. We only have one kid out). But just a moment ago, she started asking if having a past crush on a trans guy made her pan, and I admit I blew up a bit (there has been so much transphobic stuff going around in my neighbor hood, I'm really defensive about it) and I basically said she was being (accidentally) transphobic, and that her dating her current cis boyfriend wouldn't be all that different than if he was a trans guy (in terms of sexuality), so having liked a trans person isn't a deciding factor in if she is pan or not, as its not only pan people that can like trans people. Then she got all offended, saying that it wasn't what she meant and she didn't mean for me to get all mad about it, and now she is only replying with short, unclear replies, even to my apology.
She's the only one I have ever almost fully confideded my entire identity to and I really don't want to loose her. She's the only one who kinda understands what it's like to not be straight, and even has offered to help with my homophobic family members. I seriously need some help for this. I don't mind if it's links to pages that help explain transphobic language, or how I can personally help her understand.