Also, while I'm on the subject (obviously this is important to me), I would really really really try to avoid even thinking that "this is my best friend's daughter".

One thing that kids of all ages are is perceptive. Even if you think this under your breath, she will detect it and it will only reinforce her loneliness, poor sense of self worth and self-destruction.

If you're going to engage with this child, do so fully and with courage. She deserves it.

This child's mother passed away, but she did not. She can have a long and glorious life ahead of her.