This is a subtoot, and I'm sorry, but it's generally true and needs to be said:

If someone talks about suicide, please don't bring up how other people will feel or how "selfish" it is.

"Think about the harm you're going to cause other people" is a deflection that lets you not think about the pain the suicidal person is going through and the harm others have done to them, and frankly it just makes the suicidal person feel /worse/ at the lowest point in their life.