I just want to throw this out there for you to think about. And maybe you have already, maybe not. But I feel I must mention in.
The first thing that stood out to me in your post is that you were making an excuse for why your WH cheated on you, YET AGAIN, after five (*5*) years of, what is now to be considered, false R.
Have you really searched within yourself to see if this is truly something you want to be in? Have you considered the affects on one's health associated with dealing with so much constant, chronic stress? Have you taken time to really think about what it is that is making you desire to still be with someone who can continue to emotionally abuse you and traumatize you? Lastly, you mentioned MC, but do you have an IC you can talk to without your WH there? A good IC will help you get to the bottom of what it is that is driving you to stay with him.
Regardless, you are MUCH more forgiving than I am, as well as a lot of BSs on here.
That being said, provided you really have dug deep into what it is you want, and you truly do believe in this guy, then more power to you. Just keep a bottom line and a list of requirements that must be met for R. I would demand MC & IC, at a minimum, as well as access to email, phone, and any accounts not jointly shared by the both of you. And of course, this goes without saying, but absolutely under no circumstance should there be ANY contact between your WH and his AP(s). 100% total NC.
Best of luck to you. You are on a road much less traveled. Be kind to yourself.