Though I would suggest that the OP do the following first before talking to the student about college finances:
a. Figure out what financial aid situation the student will be applying for financial aid as (e.g. independent or dependent student, etc.).
b. Figure out how much the OP can comfortably afford to contribute if the OP wants to contribute to her college costs. This may require some financial planning that the OP has not yet done.
c. Run some net price calculators on some colleges of possible interest (e.g. state flagship, local state university, private colleges commonly of interest to students in the area, etc.). But be aware that some colleges’ net price calculators may be less accurate for unusual situations.
The above can be done in the background without having to talk to the student about college at all. But then the OP will be ready to have the college finance discussion when the student is ready to start talking about college thinking about making an application list.