Either folks are getting more hypocritical, or we're simply becoming more aware of it.
Ol' Meniscus here keeps her faith close to the heart. I've always been wary of those who shove it in the faces of others — seems like they're overcompensating for something.
Regardless, you already stated the answer to your dilemma. For your emotional health and the stability of your world, you need to leave this lying, two-timing hypocrite, and stand on your own two feet. Do it out of love for yourself. Someone is out there who will love you truly.
And for heaven's sake, do it out of compassion for his wife — think of the torment she's gone through, and you're contributing to that!