Can I just say, and I'm just being honest...

[Mystical]

Well.. this is the CIJS thread but I'd suggest that you figure out how far you're willing to include yourself in their business, ie: would you be willing to encourage and help her follow through with an evaluation at her local walk in clinic? Every city has some form of urgent mental health services. Like crisis hotlines and clinics that help with crisis intervention.

You can take her in, at any time, for emergencies, to the hospital emergency department too. She'd need to be complicit and honest with the assessor though amd tell them shes afraid for her safety (suicidal or wreckless endangerment kind of tbing) unless she's hurt herself in which case that's an automatic hold. Honestly my mother has gone this route several times this year and I'm happy with how the police/hospital/mental health facipity handled things.

Or on a less urgent level I don't know a single state mental health clinic that doesn't allow walkins for people in duress. Suicide prevention definitely too has resources.

If anything just giving her the numbers could save her life, if you're scared of her. Personally I don't tolerate chronically suicidal people in my life. Either want to live, or go be suicidal elsewhere. I've had family kill themselves though.

If she seems removed from reality it's possible that contacting some one in her family might be good, but as I said not everyone is willing to allow suicidal behavior to dominate their loves by keeping those relationships. It's not healthy for either party. Sadly, the isolation is part of the disease and it adds to the person's sense of despair. You aren't captain Save the world, but there are things you can do to help if you feel there needs to be some intervention.
Hallucinations are serious indicators, depending upon the mental illness she's dealing with. For instance if she hallucinates you as someone else who has hurt her. Or hallucinates her abuser talking to her and telling her to hurt herself or something. Even just having the hallucinations creating paranoia could put her in a self-preservantion mode and so I'd advise not going near her if she has access to weapons.

Just my 2c for free