What to say to someone who is sucidal .

Hi... so I’m 17 years old and need help with this topic. I have prevented a couple of sucides but I’m at the point where I need advise on what to say and what not to. I have a few things that I always say but I need your input on this to get better things to say. Please don’t tell me to tell an adult when people are sucidal and that I shouldn’t be dealing with this myself. That’s my choice and I do inform an adult but they can also make the situation worse so I keep them at a certain point close enough to help if needed but far enough to not interfere. Okay so at the moment I have three friends who are. It’s not something that can be fixed so they have given up , they aren’t link but it is by chance that they all have the same thing. The Doctors don’t have a name for it because they don’t know what it is yet so they continue to do more and more test. So please give advise because I really need it this time.