Maybe she knew about at least some of it.....? Some women put up with it to some extent. And if he was a narcissist as many are saying, then he probably had ways of blaming it on her anyway, sort of making her feel like if she was better, he wouldn’t have to look elsewhere. That, or when she figured it out, he could have done the narcissist thing of making her doubt what she knew...making her feel crazy for even second guessing him.
She complimented him a lot on SM. It could have been just a SM front...but on the other hand, sometimes people being emotionally abused try everything they can to worship the person and build them up to make them happy so that things will go better in the home.
Just thoughts. This case is just heartbreaking.