How do I tell my best friend that I don't want to move out with her?

My boyfriend, best friend and I are in our early 20s and have been talking about the idea of being roommates for about a year. I love my bestie to death, but there have been too many warning signs of this being a bad idea:

- She got into a car accident (months ago) loosing her car, doesn't seem to be looking for a new one.

- I cart her to work multiple times a week because of this (over an hour away).

- Said rooming is a great idea because "if you're ever behind on rent, your roommates can always back you up!"

- Already owes me money I know ill never see again.

- Refuses to learn how to cook for herself

- Spends money going out every other night

- Missed payments on her loan, therefore has bad credit

- Recently stated after using the atm that her "<1.5k balance wasn't too bad"

She has an offer to move in with her inseparable (boy)friend for much cheaper, but won't because they're not in a relationship yet. I planned to view an apartment with my boyfriend tomorrow, so I need to address this right away. How should I go about telling/convincing/"intervention" her that she's not ready without ruining our friendship?

Thanks!