Dear Sophie,
I was saddened by your post, not only because your friend has said things that you found so hurtful but also because you feel that a 10 year friendship has come to an end because of it.
Acceptance is always going to be hardest amongst those closest to the transitioner - the mother & father who still see their son when others see a woman, the friends who cannot envisage a friendship with a woman who they used to enjoy lads' banter with etc. etc. - but society isn't helping the cause either.
We can draw some parallels with the gradual acceptance of homosexuality to the point we're at now where gay and straight people enjoy identical legal privileges, and an increasing majority of the population don't feel the need to make sensationalist jokes or comments when discovering a friend or colleague's sexuality for the first time. However, this has been a very organic process evolving over several decades without excessive intervention from the authorities.
Conrast that with trans issues where, all of a sudden things have exploded and it only takes someone to say 'I identify as a woman' for the authorities (be they councils, government or the local swimming pool management) to go into a tailspin and, of course, it's the more extreme cases that get reported in the press whipping people into a frenzy and resulting in the type of attitude that your friend articulated. The problem is that someone who is totally comfortable in their assigned gender will never understand the anxiety resulting from dysphoria which, in cases such as yours, gives an overwhelming drive to transition.
Will the situation change? I firmly believe it will but it will change as a result of positive moves within the majority of the trans community rather than by dictat from a small but vocal minority of the community or the government. I can think of five transwomen in the UK who were public figures prior to transition - Kellie Maloney (formerly Frank - boxing promoter), India Willoughby (formerly Jonathan - television newsreader), Victoria Smith (formerly Vince - jockey), Philippa York (formerly Robert Millar - cyclist) and Stephanie Firth (formerly Simon - radio DJ) - and, with the possible exception of Ms Maloney, all have represented the trans community in a very positive way and have successfully returned to their former careers in one form or another.
My point here is you have a part to play in this. You can educate your friend by taking her with you and, who knows, in time she may become your greatest advocate. That's not to say that you must stay silent if you disagree with her views of find them offensive but, by explaining why you find the views offensive will earn you far more acceptance than you will get by cutting her off. A key part of transition is gaining acceptance and I am absolutely certain that there will come a point where she can accept you for who you are, not who you were. I hope, therefore, you can give her a second chance to join you on your journey.
With my best wishes for your future happiness and success.
Amanda