The Perplexing General Petraeus Resignation

I can't remember the last time when such a well-known public figure outed himself as a two-timer on his wife but, General Petraeus, the head of the CIA, did just that.  And, it was done in the midst of an increasing controversy over the Benghazi consulate attack and the killing of four Americans.  Certainly, Petraeus' CIA was highly involved in this incident since the CIA dominated our presence in Benghazi.  The "annex" that is always being talked about -- just a mile away from the consulate --  was a  CIA installation.  Two of the four dead, Tyrone Woods and Glen Doherty, were former Navy Seals under contract by the CIA and stationed at the annex.

Normally, an affair becomes public and the offender -- after the fact -- has to respond with some public affirmation, humility, and an apology.  But, because Petraeus came forward before any public knowledge of his affair, it almost seems like he was being blackmailed in some way; and, he decided to thwart the blackmailing by going public on his own.

This, then, leads to other speculation.  Was the threat of a public exposure of his infidelity being used to force him into "modifying" his upcoming Benghazi testimony before Congress?  Perhaps, take the fall for the Obama Administration? Certainly, the timing of Petraeus' disclosure and resignation would suggest something like that.  If so, was this an extension of the currently suspected coverup over Benghazi?  And, at what levels within the Obama Administration was this "blackmailing" effort being conducted?  Was President Obama involved?