The best kind of help you can provide is to tell her that you love her and you are sorry she’s in so much pain. Tell her that you would miss her dearly if she were no longer in your life. Tell her that you wish that you could make her feel better right now, but she will just have to wait a little longer.
Most people who have been moderately depressed have considered the reprieve that suicide promises, and they are usually relieved to find out that others know how common suicidal thoughts are in unipolar major depression. Even if your loved one is not open to discussing her feelings now, you will have opened a pathway for communications that she can use if her suicidal thoughts and impulses escalate in the future.
You do not have to mention suicide by name if you are uncomfortable talking about it. If you are comfortable discussing suicide, do so with calm caring. It is okay to tell depressed people that you hope they do not kill themselves.