Welcome here to the forum, I'm sorry you have had to go though this.
Some people are not friends, it is as simple as that, and there is little one can say about the reasons why she had changed based upon your post. Perhaps she did not know you were trans to start with or perhaps she has been frequenting with bigoted people - who knows.
The important thing she is simply downright cruel, and such persons should be shunned, their toxic nature is bad for all who come in contact with them.
Do you have other friends or family to support you and care? If it was me, even if I did not have anyone else, I'd sooner be by myself. There are plenty of good people to find.
Do you mind if I give quote from the Desiderata? You may have heard of it, a gentle non religious philosophy set down on paper. I look at it in troubled times to find comfort that others have faced the same troubles as me and gone on.
Avoid loud and aggressive persons,
they are vexations to the spirit ...
...You are a child of the universe,
no less than the trees and the stars;
you have a right to be here.
I hope you find others here who you can relate to, it is a gentle and healing place