I have experience with this situation through relatives and also through others close to me who have gone through this. Unfortunately in all of the cases, the Parents were exhausted blaming themselves and looking at their behavior and ultimately nothing they did made a difference. I don't know that you can fix this problem. I know you want a solution, but there may not be one other than finding a facility where he can live until adulthood. Sometimes there are relatives that can take the kid, but I can tell you from experience your child will only get worse at times goes on. His issue is nature not nurture and that's very hard to fix. ADHD might be an issue, but it's not THE issue. People like this must be compartmentalized to minimize damage to the family. Your other kids should not have to suffer and ultimately will. I know one person in particular who had thier oldest child suck the life out of their family until he was kicked out. The younger kids still resent the neglect they suffered and don't want the older sibling back on any terms. I say this with no glee, or am I trying to tell you what to do, but this is not your fault. You didn't create this problem. Your child has an issue they were born with, and need help. Long term mental care like you would if they were schitzophrenic is best. Admit to yourself and your family that this will not get better and let yourself off the hook. This will not be easy, but you are a good parent and know that you are doing your best.