Facebook and ex-boyfriends don't mix, it's just a fact. Thanks to public outcry, the social networking site is now doing its small part in the healing process by keeping your nixed fella out of the "Photo Memories" box. But there's still the ability to stalk each other and flirt with old flames, unless you decide to de-friend or block him for good, which isn't always easy but can be the best solution.
I've just heard too many horror stories, like one friend whose ex commented a "delete" under certain Facebook photos and then told her she needed to remove all photos with a "delete" under them. Or the friend whose ex has a serious girlfriend and yet is the first person to comment on every inane status she puts up (see photo above, real status, real ex response) and leaves inappropriate comments on her photos (e.g. "You look very beautiful and sophisticated in that photo. ;)").
I'm wondering, what's your worst example of Facebook plus exes equals disaster?