Don't accept the blame. Don't even think for one minute YOU are in any way responsible for the bad choices your son has made.
I wish I had someone tell me that in the beginning of our highway to hell!!
He knows that you are not to blame but they try that anyway. Kids like this have NO sense of self awareness and look to everyone else to blame for their life that is not going like it should. They may be intelligent (my son tested with an above average IQ - whatever that means) but have a hard time making the connection between bad choices resulting in bad things happening and a bad life, parents 
ing etc. When they realize THAT, then some change can be seen. My son is just starting to understand it and he is 21. I've talked til I'm blue in the face and I'm DONE. Figure it out dude.
