Hey, I know that I am the 'Ultimate Prick'....but its a self description!
As for your son..I dont know what is the right way or the wrong way, but here's what I would do if I were in your shoes.
I would simply write him a letter that lets him know how much you love him, even though he treats you like dirt. He is a teenager, right?.....you know how teenagers just know EVERYTHING, right? Well, the best thing to do is let him think whatever he wants, because trying to change his mind or argueing about things is only going to make him resent you even more.
So what do you do?....you put the ball in his court. Write him the letter, let him know that you love him dearly, and that he's always in your thoughts. Tell him the happiness and joy you felt when he was born, and that you still have that joy for him no matter what. You see where Im getting with this? dont make any negative comments towards him or his attitude, let him know that you think he's great just as he is.
He may accept this or he may reject it....but he wont forget it.
It may take him a few years to realize what a rotten kid he's been to his mother, and then you will start to see a change....a change for the better! Sooner or later, his conscionce (sp?) will catch up to him and he will want to re-establish a relationship with you.
He will have much more respect for you than he did in years past.
And if none of this works, then you can just walk away from it all and let him live his own life.