How to help a friend?

I have a friend that I met a few months ago that I really like and care about but they have mental problems that are pretty far from mine so I don't really know how to help them. They have a big personal celebrity worship syndrom alongside with depression and suicidal thoughts. They are obsessed with a lead singer of a band and they talk about suicide more often now. I am really worried that they can actually take their life because of that. All their life is about that celebrity and I know it's not healthy at all but I am afraid that if we do an intervention and try to make my friend think less about the singer, they will lose any reason to carry on and stay alive. Any piece of advice would be helpful