Girls...girls like this, they tend to be great, interesting people, but they also tend to choose horrible people as partners. This isn't a coincidence, or that being an unbearable asshole is some sort of magic formula. They find assholes attractive, not because it's universal, but because they associate jerkiness with attractiveness or love. Abusive or neglectful father figures, or the first person they were in a relationship with was abusive or neglectful. It won't work because like Lorenz's imprinted ducks or Pavlov's salivating dog, they have the mental defect of associating abuse with love and affection. They don't know how to deal with kindness, and they don't associate it with love. No matter what, you will never win over this type of girl be being a good friend.

I know this because I have fallen for this type of girl before, and at different ages; a 17 year old one like this in high school, a 22 and 23 year old in college...and most recently, a 36 year old woman like this. They never change, they float through life on dozens of failed relationships which turn exploitative, abusive or neglectful, and never seem to see the cycle of destruction, because they're unconsciously programmed for failure.

I say, tell her what you need to say, expect the worst, (with the tiniest hope for the best), and move on (or forward).