not bad advise

I don't know about blackmailing her, that's never cool, but if she's cheating on you it might turn out to be really handy someday to have a video of it. It might allow you to keep your house or get you out of alimony payments. Don't say it couldn't happen either. If she's fucking other guys behind your back it definately could. In my experience women tend to fall in love with the men they fuck regularly.