This is unfortunately part of their playbook. Same thing happened to me, her saying "I have decided I'll stay in the M", with a superior tone, as if everything had been my fault. My mistake was to behave as if it had. I was so focused on getting her back I didn't realize I was playing precisely into her fantasy. It turned out all she did was take it underground.
IMO, he's pouting because he never faced consequences before, and the bankruptcy is the first real consequence he has faced.
Read "not just friends" by Glass. Also I just finished a book called "Boundaries" by Henry Cloud, it's really making me understand a lot about why I was "too nice" and why that was damaging to both the M and the relation. I think it would help you to take a look at it. For his issues, read up on narcissism. "Disarming the Narcissist" and "Splitting: protecting yourself while divorcing someone with NPD " by Bill Eddy were very helpful to understand the mindset.
It seems to me he's using his anger and pouting to control you. Don't let him - know that is intentional. 180 him. Go see a L (there is free basic legal advice for family law at your local courthouse, ask around) and start showing him some consequences. Someone here said that you must be willing to end the M in order to save it. And even that is only 50%. The other 50 has to come from his remorse and willingness to stay without anger, ready to help you heal for a change.
Note he may leave you. He may not want to change. But the world that leaves him Scott free will end, and by facing consequences he will either go to the OW to start oppressing her or snap out of it. I am S (D is almost final), and she stopped using anger to control me once I stopped all verbal contact (written about finances and kids is ok and I do it businesslike). Now the few times I see her she's polite. But it took months.
Either way there is some work you have to do on putting limits on people for your own happiness. He's abused you enough.
The dynamics are so similar in all the cases (even across genders) it's stunning. That's why we call it the "playbook".
You're being listened to. And we all feel like you at one point or another of this nightmare.