any tips on how to keep going when you're exhausted but will never, ever let go or let down the person you're caring for?

My friend is confusing my attempts to marshal more resources as a rejection of her, when it's just the opposite: I want to go the distance with her but know I can't make it without more help. My attempts to discuss this with her are making her confused, distant, depressed, and suicidal. Her illness is causing mental confusion, so it's almost impossible to have a rational discussion with her, and she is so fragile.

Help!