Friends can help but sometimes what you are going through is too big to handle by yourself and you need an adult to get involved.
But who do you ask for help?
What do I say to start the conversation? Aren't they going to think I am crazy and need to be in a hospital?
Most adults will try and listen to you carefully and offer you their support. They will also have a good idea of where to get help, and if the matter is serious they can go with you to talk to the police or appropriate agency.
If you feel that the adult you have chosen is unresponsive, not taking you seriously or is being judgemental then you should thank them for listening and walk away. Some adults have their own issues with suicide any they may not be a good choice to talk to about your concerns. You should always try talking to another adult and not give up, your concerns and feelings are real and important and they deserve to be heard. You can also talk to someone at one of the national helplines 24/7/365.