In 2010 we separated for a year and she had two affairs. The first happened after a month of me moving out. She continued to flirt online and like men to give her attention.
Remember this ^^^^^^? I don't think it's all about your porn addiction. That gal has some addictions, herself. Was she into chat rooms, online dating sites, etc.? I would be willing to bet a month's salary you don't know half of what she does under the category of flirting and getting men's attention.
Your porn probably paid a big part in the breakdown of the MR, but I don't think it is the only reason.....or maybe even the true reason....for her wanting a S/D.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!