Hi Cat, I believe you should inform law enforcement. She should get professional help as soon as possible.
For now, here is a national suicide hotline:
1-800-273-8255
Here is the site you or she can also go to:
https://suicidepreventionlifeline.org/
They have people trained to handle this and resources for them to use.
Now, ask her the following questions:
1. Do you know if she has a plan in how to kill herself?
2. Do does she have any means to kill yourself?
3. Do you believe she's going to act on it now?