Meh... this one is simple. Petraeus knows what happened with the whole Benghazi thing. He wants to talk because it pissed him off so damn much that he was going to resign as head of the CIA and open up to congress and the public.

Obama administration did not want that AT ALL. So they threatened that if he resigns and opened his mouth that they would disclose his affair(s) publicly and destroy him. So instead he disclosed it himself publicly (and in his letter of resignation) and killed the effects of blackmail. The Obammy administration now has no control over him, he shot himself in the leg instead of letting them continue to hold him hostage at gun point.

In time I think this whole thing is going to blow up and cause a lot of damage. Or it will go away for awhile and Petraeus will write a book an disclose it there and bring the issue to the forefront again.