Then you shouldn't have kids; he had six of them. It isnt like this happened overnight , and I am sure he had major issues before some if not all of them were born. He was rich and lived in the US, so he had the best possible treatment options for addiction and depression.
His depression, at the very least, was exasperated by drugs use (if not the main cause of it). But there is no way to treat depression if you continue to use.