The life of a transsexual is very challenging. She's gone through a lot to get to where she is. She probably feels that cross-dressing is superficial and cowardly because at the end of the day, the m2f crossdresser retreats back to his mountain of masculine privilege, and perhaps has fewer deep identity crises associated with it. But the truth is everyone has their own battles to fight, and it wasn't right of her to belittle yours. That said, in that situation I would put myself in her shoes - you may find that what she really is lashing out against is her own insecurity and angst for self acceptance. Her insistence on creating an 'us versus them' dialectic would tell me that she is quite concerned about her identity in relationship to others. Being TG, my own experience is that I tend to be very very sensitive to gender and gender identity. Maybe she had a bad day, bad week, or bad year... this sort of pain can really drive any person to bitterness at times.
Her wanting to make you pass seems to me to be little more than another chance for her to exert her superiority complex on you, but it might prove to be an opportunity for her and you to communicate openly an honestly and perhaps both of you can walk away with more respect and love for each other's individual situations.