MLCers play the victim to perfection. It is their starring role. And how boring for OW
They do not think about what they are saying and doing - they are running on overcharged emotions, like an out of control teenager/toddler. And can those two age groups emote!!
It is awful for you, but it is all about them.
If you can try and laugh at his antics it will help but it is hard when they are doing so much damage. To this day my xh blames me for his poor relationships with this children - relationships which I have tried to facilitate.
They see what they want to see, not that they live in a network of responsibilities and obligations, like any adult.
It is especially hard for you because you are battling cancer. I also had cancer while this was going on, and went through the treatment (now in full remissions) so I have an inkling of how hard it must be.
Please believe me when I say that it does get better. They do calm down eventually and move to the next phase of their miserable lives.
Take care and focus on getting through your own ordeal. I can assure you that no decent person is impressed with your husband's antics