You can be there for a friend and still admit they need more help than you can give.

Caring about somebody and being the right help for them are two different things, and the gap between them is not a failure on your part. Some situations are bigger than a friendship can carry, not because you are bad at it, but because they need someone with training, and you are young and also have your own week to get through.

You can stay their friend and say the honest thing gently: I am worried, and I think you need more than I can give. Offer to sit with them while they tell an adult. Then tell someone yourself, so you are not holding it alone.