OK!

Since there are not suicide and self-harm problems, it is not an urgent issue. It is not an ASAP concern, so relax.

tell her that you do not think that she is insane. Instead, you think that she is suffering from insomnia, which is a common concern of a whole bunch of Americans who also do not consider themselves insane. And, for that, she needs to go see a GP (she should realize that GP's treat diabetes and broken limbs, which are not insanity issues) to get a sleep medicine. Once she starts sleeping normally, she should wait for a month to stabilize on getting enough sleep. If after a month of sleeping normally, she still sees images in the mirrors that do not reflect (no pun intended) reality, then she can talk to you again. But she first has to stabilize her sleep. Until then, she should not talk to you.

What she is doing to you is emotional rape. She is forcing you to listen to her accounts of her near insanity, and yet fiercely resists your attempts to help her by claiming she is not insane. You need to point it out to her and make a deal with her: either she reports instances of being insane but then accepts your attempts to help her, or, she sticks to her self-identification as a person who is not insane, but then refrains from reporting hallucinations to you - EITHER OR!!!

The victim here is YOU.