I saw this on fanfiction.net too, and liked it very much.

What *would* you say if you were a nice person, really, and you found out Clark Kent's secret? You could destroy his life if you blabbed. But you don't really want to. And yet you do have the urge to tell him that you know...and then to realize that you're just one of a thousand victims saved.

And yet, Margaret goes through with everything and says "thank you". And by providence, it comes at a time when Clark really needs that something extra to go on.

A fine story.