Confused on the 8 Mile movie?

So i watched it for the second time, and im still kind of confused
about some stuff:
1. Isn't Kim Basinger his wife/Halies mom? (Ex-wife?) And if she is,
why is she portraying his mom in the movie?
2. Is Janeane meant to be Kim? Or is Alex?
I LOVED the movie im just confused about these things, thanks!