Here's the question - is it LEGAL to expose a cheater or abuser online? I remind you that this piece contains my personal OPINION only and was written for the purpose of consideration and discussion.
In short, it appears the current answer is YES. But this could change in the very near future.
Most of these type of sites have rules for exposing the people listed. The current interpretation seems to say if you have proof to back up what you say, and it is truthful, it is not libel or slander. But remember, laws can be changed with enough pressure.
Recently I was asked if most of these abusers and cheaters feel ashamed, sorry or sad about what they have done. My answer: "Not that I have seen!! In fact, it seems that they usually become indignant, angry and lash out at the person(s) that exposed the truth about them. They only "feel sorry" to try to rope the victim into saying nothing about them and to stop the tide of truth from exposing all the rest of their evil deeds." Sad? Yes they are. Sad they got caught. And some of them do clean up their act for a few weeks, months or even years - but usually go RIGHT BACK to it and are sneakier about it next time.
If you consider that many of these people fall into a destructive narcissistic pattern you will find that many of them will go to therapy or even make long confessions to their partners. Once they find themselves "CURED" (I use that term loosely because deep down they justify and see NOTHING wrong with their behaviors) they will, step by step, go right back to their predatory ways either online or off. Being an online cheater is an addiction and takes a lot of honesty and giving up personal time to break an addiction or not trade it for something equally addicting and destructive.