> The family (not my wife) asked me to talk to my brother-in-law about this because nobody else could get through to him.

I am a stranger on the net but your first priority is your wife and your relationship with her. Be very cautious with demands from the family even if well meaning. Protect yourself and your relationship with your wife.

When going through a similar event, I was able to find resources at the hospital that helped a lot. In life and death situations they often have patient advocates on staff. I was able to reach out and had a patient advocate, either a nurse practitioner or doctor, that helped sort out the communications. A lot of the stress came from doctors' reluctance to put things in simple terms. The patient advocate was able to basically come in and say, "Look, they can put a pacemaker in, but your loved one only has 12% heart function and is still dying." It was received differently than a family member saying it. After all, their job is to advocate for the best interest of the patient. Ours actually got pretty angry with the doctors for how things had been allowed to progress. Hospitals usually have grief counselors and social workers as well. Just getting the brother extra support might be enough to open him up.