Yeah, he's 50% responsible to be exact. Why on earth would it not be entirely plausible to say 'H, I will not stay in this R with you any longer unless you agree to MC'. Why would that not be considered a boundary? He has free will in this example and so do I.
A boundary is something you place upon yourself, not on another. You staying in the M is conditional upon a specific action you've established for him. That's a power play.
A boundary would be: "I can longer stay in the Marriage as it is." If and how he changes is completely up to him.
As for being a victim... you have admitted to and accepted responsibility for your transgressions, you've apologized, you've gone to MC, and unless I'm missing something, have done just about everything one person can do to bring about change.
The victim aspect I see is where you continue to pay for a 'crime,' over and over again. You are 'powerless' to change the situation, for he will not allow for change. But just because he doesn't allow for change, doesn't mean you have to employ power play tactics of your own.
Once you recognize that, you don't have to be a victim any longer. If you choose to remain, and cry 'poor me,' for deciding to stay, you are a martyr. (just by way of definition, not saying you are doing this).
And I would have said what HP did, but she already said it, so I don't have to.
