I agree with Aussie.....you son is hurting inside....just when he needs a role model most in his life, he has none......and he's angry...I'm sure he thinks part of the reason his dad is gone is because of him. He feels accepted with his new friends..something he isn't getting from his dad.
I wish more men would realise how important it is to be in their kids lives...There is a huge diffrence in being a sperm donor and a father.good luck...get some help...I wish you luck