When I signed up for Facebook, I made a personal rule never to friend one of my students, bosses, or ex-girlfriends. About nine years ago I got a friend request from someone I had a serious relationship with 30 years before. (She's the one I mentioned in the ""Worst Breakup" thread.) Her last name was different and I didn't look closely at the picture, so I just deleted the request, not realizing who it was. About two weeks later, she sent another, along with a message saying "Long time no see, how ya doing, etc." That's when I realized who it was. I didn't respond - I just deleted the request and message. I did check out her public profile, though, and found that she's divorced, has a kid, and still has the same core values that ultimately led to our relationship going sour.
We broke up on bad terms, but I don't hold a grudge. In retrospect, I suppose I should have at least responded to her message without accepting the friend request. Then I could have made Jauronimo happy by telling her about my successful marriage and career.