Jo,
My heart goes out to you. I have a friend who has 2 sons age 21 and 19. She has been a mentor to me with DS13. One thing she has stressed is the boys need to vent energy. She strongly advocated sports. Her boys were on the high school basketball and football team. We found that Tae Kwon Do was a great outlet for our DS. (lots of punching and kicking. Our do jang (studio) also did alot of teaching on respect for parents and teachers. DS spent about 1 1/2 years in Tae Kwon Do. The first year he loved going and it let him blow off alot of steam. He lost interest this year. (I think it was because of the contact phase of his training) He also plays intramural sports.

Disrespecting adults is not acceptable behavior in our home. We have found what DS values (computer, internet, video games) and it is taken away as a consequence of misbehavior. This has been an effective means of discipline for us.

I'm including a link to Dr. Phil's website. He has some sage advice with dealing with TEENS. Hope you can gain some insight on what to do.
http://www.drphil.com/advice/advice.jhtml?contentId=parenting_teens_trou...

http://www.drphil.com/advice/advice.jhtml?contentId=par_discipline_ageap...

My prayers are with you and your family.
Susan