Scarleteen

I think I would like to talk to a close friend/coach about myself being sexually assaulted. Will she have to tell anyone?

You need to ask them that. "Have to" is about if someone is or isn't a mandatory reporter, and what that entails for them. If they are not someone in a job where there is mandatory reporting, then there is no "have to," only a "might." So, either way, you just want to ask.

You can do that without disclosing until you know their response by asking something like, "If someone were to talk to you about some kind of abuse or assault, is that something you would have or want to tell someone else about?" That says what you are asking about, but it doesn't tell them you're asking about yourself.