Bren, that sounds like addictive rationalizing to me... I say he's just making excuses to justify his infidelity.
Think this through
a. He abandons a woman with a fatal illness for another woman b. He claims to now feel as if he's betraying a deceased woman when he has sex with you c. For some mysterious reason though, him abandoning YOU does not produce any guilty conscience in him at all?
How is it he can logically feel guilt for betraying a woman who isn't even experiencing abandonment now, but he doens't feel guilt while he knows he's hurting you?
Wayward spouses having affairs Bren make up a million and one excuses for JUSTIFYING their affairs.. both to ease their own guilt, and in the hopes you will back off and let them continue their abusive affair.
There is a huge list, I won't reprint it here, trust me we have heard them all... This is a variant of the same senseless excuses we normally hear during affairs.
MWD makes it quite clear you do NOT listen to what they are telling you when they are wayward... in my opinion this goes DOUBLE when they are cheating.
Further, infidelity is an ADDICTION... addicts will tell you anything to keep up their destructive habit.
He's trying to convince himself AND you that what he's doing is OK because of your past history... He has the twisted idea in his head that what he's doing is OK, because he's not betraying anyone when he's with OW... You agree with that Bren?
If he is sincerely remorseful and has expressed willingness to end this, but keeps going back then maybe threatening to expose this publically might be more effecitve.
I do NOT often do that because what this usually results in is the WS going to everyone FIRST and exposing the LBS as mentally unstable or some such... Basically a smear campaign to invalidate the testimony of the LBS.
I would have to think on that, If you informed him that if you catch him cheating again you will let the network know what he's doing how would he react? Would he start exposing YOU as unstable to everyone first or something like that?
You basically need to find some leverage. If he falls off the wagon you crack down, HARD... Show him what happens when he betrays you... NOT to hurt him, but to IMPRESS UPON him that you will NOT TOLERATE DISRESPECT, that CONSEQUENCES happen when he cheats.
This is basic conditioning here. The more he cheats and you don't bring down consequences on him, the more FREE and OPEN he will feel he can be.
Each time he cheats and gets caught...and NOTHING consequential comes of it, he will feel MORE CONFIDENT that he can continue... He will cheat more, and be more excited about the idea... He will feel you are supporting his cheating by NOT interfering.
And verbal chastizement, tears, etc will NOT count for zero. He is convincing himself that what he's doing is legitimate.. At least MORE legitimate than being with you is.
It's all rationalizing the truth - he's addicted to this fantasy and won't wake up.
He needs YOU to WAKE him up with some COLD HARD REALITY