I was confused by the title of the thread after reading your post, he sounds like a perfectly normal 19 year old to me, boys have a tendency to lose a bit of reason between the ages of 16 and 21, at 21 or thereabouts you will get your beautiful boy back
He's not a dark entity just a normal kid, the period between boyhood and manhood must be incredibly confusing and frustrating for them, if you feel your temper rising, walk away, even if he does get the last word, remain firm if he is way out of order though.
When going through this they need someone strong to 'kick back at' but don't let him overstep the mark, if he rants calmly tell him you will continue the conversation when he can speak to you politely and walk away, this time in a boy's life is tough and harder to cope with than any girl's tantrums, stay strong, that's what he needs.