Nobody knows that I am suicidal, and I do not share any of my suicidal thoughts with anyone outside of this forum. As a guess: I am under the impression that other people who see me regularly in the real world, like acquaintances, just think that I am an asocial loner - which I am; I do not believe that they would go so far as to think that I am suicidal though.
As for their reaction: shocked or unsuprised? I do not want anybody knowing in the first place. Plus I am no one important, so it is unlikely that too many will be seriously upset anyway. Though there might be virtue signallers as is the case with many suicides.