You’re absolutely right. You are way, way over your head. It’s not at all unusual for a therapist to say at the outset of treatment that everything is confidential except when someone tries to hurt themselves or talks seriously about hurting someone else. We want to make it clear that in that event the rules of confidentiality are off and we will take action. Saving lives takes priority over keeping secrets.
Your camper is underage. You are not a professional therapist bound by professional rules. I therefore strongly urge you to call this girl’s parents and turn her care over to them. Tell them what your camper has told you about the boyfriend. Inform them that she says the counseling she is getting isn’t helping her. As difficult as it will be, tell them that she has told you that she has made two suicide attempts. It may or may not be true but even making up stories about attempts is concerning. They deserve to know how serious the situation really is.
Then let the parents take charge of helping their daughter. Don’t, don’t, don’t feel guilty for taking action. Yes, she will blame you and will tell you that you have betrayed her and abandoned her. She may say that but it isn’t so. It’s a much bigger betrayal for you to go on trying to be a therapist when you have neither the training or experience to be effective. By talking with you, she is avoiding dealing with her issues with her therapist. You need to get out of the loop. If she contacts you, keep it short and to the point. Tell her that you do care. Actually you care so much you want her to get real help instead of the minimal help you can offer. Don’t get into an argument about it. Just let her know that every time she calls you, you’re going to inform her parents. If she keeps it up, tell her and her parents that you won’t respond anymore.
Therapists all have supervisors just for situations like this. We need support to keep our heads clear and to do what is most useful instead of what a desperate person demands. It’s hard to say no when someone is so upset. It’s hard to pull back if someone says you’re the only one who can help or that she’ll hurt herself if you won’t continue to be there. If you think you can’t extricate yourself, it would be advisable for you to see a therapist to act as your “supervisor” for this case. You’ve done the best you could. Now it’s time to let the experts take over.
I wish you well.