In a pro-life society telling people you're suicidal is likely to result in either being dismissed, belittled or cause a moral outrage and excessive worry which might result in some sort of punishment, which usually means fun & games at your local psych ward.
Also people might interpret sharing suicidal intentions as a cry for help or even emotional blackmail as in, help me or I'll hurt/kill myself. Often they're not completely mistaken. This is merely my opinion and observation and not a judgment of those who do this. Desperate situations create the need for desperate measures.
Please keep in mind that attempting ctb or even declaring concrete and life-threatening intentions of self-harm is de-facto illegal in most countries. Take a look at your country's mental health legislation. You get no lawyer to defend you, no trial, just the expert opinion of a doctor. I'm not saying it would be any better if suicide attempts were handled like "normal" crimes, it would probably be even more tragicomical than the current proceedings.
To answer your question, I have told a couple of people about my suicidal thoughts and it's been mostly counterproductive for me, them and our relationships. Even posting here might backfire disastrously, but I'll take my chances.