tablewithoutpity

Typically people are institutionalized because they are a danger to others or themselves. "Danger" to themselves being somewhat broadly defined. If you were unable to function due to this singular hallucination, then a case could be made. Likewise if she were telling you to do things you would otherwise find abhorrent. Or if you were entirely unable to distinguish the reality inside your head from that outside your head. But it sounds to me that you know this is a hallucination. And that it in and of itself is not interfering with your ability to function. Indeed, from what you've told me, it would appear her presence is helping you to function.