You have every right to be royally pissed at the person who “outed” you. If I stumbled upon such information about a co-worker, I sure as hell wouldn’t tell anyone. It would be rude and creepy of me to do so. Whoever did this to you is a slime, and a good rant about them is totally appropriate.
But I agree - paranoia and caution are good things - use them. Learn from this experience. Be grateful that you had understanding bosses. Maybe next time you won’t.
Personally, my main “outing fear” is that people will find out exactly how mind-numbingly ordinary and boring my life really is. And yet even I am paranoid about putting any personal information about myself on this message board. (Though I do provide my real name on my domain web site, but it’s just a photography site, so it isn’t exactly controversial!) Basically, I am SO paranoid about what I put out on the Internet. And I don’t care if I am being paranoid. I think it’s better to be overly paranoid than to hope that people will do the proper and right thing with whatever information they find on the Internet. Because I’ve learned - they often don’t.