How can she be so callous?

Well I have this friend who is practically family because we're so close! (Im 18, shes 19) But over the years, shes always lying! whether its about getting a sports car, or having 5 horses, to all these different boyfriends that shes had! and in a way, I know why she does it...she wants the attention and people to like her! But what she needs to realise is that shes our close mate so we dont care about anythin that she may or may not have! Anyway, weve all put up with the lies until a couple of weeks ago when she said that she was pregnant! but then when we went on a night out, she was drinking vodka all night, and when i told her she was an an idiot, she basically told me to leave her alone! But just over a week ago, everyone found out that she was lying about being pregnant! Her boyfriend (well ex now) was really upset, cuz he thought he was going to be a da! who lies about being pregnant to the people shes meant to care about! and then because we refused to talk to her for a few days, she had a go at us!! But then she just turned on me! A month ago, I had a miscarriage - i was just over a month pregnant! Of course, i confided in my friends, as well as my boyfriend! And because she turned on me, she said that i shouldnt think that shes a bad person, when i killed my own baby! And that it was my fault that i lost the baby! Its not just that, but shes been racist to my boyfriend..to his face! How can someone go from being your close mate, to completely becoming like an enemy? Should i talk to her about it, or just have nothing to do with her from now on? I cant decide, shes been a friend for years, but is what she said too unforgivable? xx