Family dynamic be damned if you are helping this man out because he's related to your adopted son and it's going to make you slip into drinking he needs to go. You and your wife are foremost here. Your son will understand it may take time. Obviously if it was the son causing the behavior that's different but an outsider you took in? Sorry his life has sucked but not your fault or problem. Don't ruin what you have trying to clean up someone else's problem.