So sorry to read that you've had some stressful times helping your mother. At least you now have the power of attorney and your brother is POA. These actions should make you feel a bit better since you live a ways away.
As for Matt, sounds like he's waking up a bit. He feels old because he's abused his body with drugs and alcohol over the years and yes, his crisis took a toll on his body as well. In time, as he heals from within, he should start to feel better with respect to his health and mental well being.
As for his anger issues, he needs to see someone about that. He needs to find ways to deal w/that anger in a productive way, i.e., work it out of his system.
I think you are very wise in not making any promises to him about the future. After all, it's just been a few months since he has started to wake up and until he has gotten himself away from the OW and on his own and doing what he needs to do to fix himself, he could slip back into the tunnel.
Hopefully, in time, he will grow up and become a more mature, grounded man to his family.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
