I feel you there, the polarization is becoming increasingly dangerous. Not because ideologies clash; that's always been the case. But because of the sheer resistance to anyone actually questioning what they believe. Your friend's response is a classic example of that - rather than deal with what you're saying in a reasoned way, they completely shut down with the "I don't know how to talk to you (anymore)" bit, which is really just an excuse to end all interaction lest you inadvertently cause her any cognitive dissonance by questioning her views. It's a sad state of affairs when friends are torn apart, not even because of some deep-seated ideological difference, but because of questions about some pretty absurd aspects of a particular shared ideology. Then again, as a leftist, I know the depths of leftist infighting over trivial shit, so, I guess it's hard to be surprised, but still that shouldn't be ending close friendships.