It's sad to read about your brother's situation and I can understand your helplessness in watching this train wreck.
Individual counseling would be very helpful in this case. I've had counseling in the past but had to be repeatedly whacked over the head even after finding out that the former spouse was living with his mistress to finally go. The encouragement came from all sides. The message I finally heard, "You have a choice in how you process this.. going to a professional and using the tools provided or mucking through it on your own. If you had a broken bone would you try to fix it yourself or go to a doctor. Your decision."
May I suggest you stop trying to be the avenging angel and DB your brother. He needs someone to listen to. He's in a world of hurt and confusion. Two of my siblings were great during my divorce. Another brother who was just as wise wasn't. He let his own emotions cloud his concern for me. And tried to tell me what to do, rather than help me see things as time went on. Things I didn't want to see or hear.
What was so helpful was how my other siblings treated me. Gave me gentle direction with matter of fact statements.
Stop beating the dead horse. Your spouse will never validate what you're doing right. Your spouse is no longer your emotional confidant, or else he wouldn't have gone to her. He loved you to the best of his ability. Reality is never as bad as what you fear. The best is yet to come.
Be his brother, not omnipotent. Support him so he has the confidence to grow. Plant a seed with a single positive statement when you talk to him and let it go. Do not judge.
Look at your own anger now. Are you in counseling? If so, is it a counselor who you feel you can control? That's not a good counselor. Find someone who helps you.
That happened to me. In learning to trust her I was able to go in with no ego. My counselor's repeated "Get in a good place to make good decisions" turned the corner for me. She wasn't out to get me, she was there to help me. Heal thyself first.
You're worth it.
Something that got over my fear of going outside my belief in marriage was "consulting a lawyer to learn my legal rights." Nonthreatening and a learning process. And something that provides understanding on custody.. which is usually a wake up call for a committed parent.
