He's addicted and doing what addicts do, including blaming you for his addiction. You did not cause this. You cannot control this. You cannot cure this. You cannot save him from himself. You are not that powerful. None of us are.
It's sounds like he is already going off the deep end. I can't come up with one good thing that could come out of exposing your child to someone addicted to drugs, has guns and is prone to suicide ideation.