Yeah, I posted on here previously, too, but it got lost during the system maintenance.

My advice is to stay the heck outta other people's business, especially the private goings-on between a married couple, and not to even think about blackmail. That's desperate and vindictive. And very creepy. Also, unless you have first-hand, eye-witness, photographic and scientific evidence of an affair, the truth is no outside person ever really knows what's up between two married people other than those two people themselves. They might have both cheated, for all you know, or might have a so-called "open" relationship. It's best to just stay out of their business entirely and worry instead about your own moral code, especially if you were giving serious thought to blackmail.