Maybe.
One problem here is that the circumstances may have been set up to silence Petraeus.
- As a serving head of the CIA he could be asked about secret matters (in secret), and he could be asked for documents. However,
- As a private citizen he would not be able to answer anything without specific clearance from the CIA, nor could he present documents. Depending on how this turns out and what games the CIA and the administration play, he may be unable to testify in any significant way at all.
Also, what if the real blackmail is not just the obvious business of his affair, but also the ongoing investigation of himself or his mistress for security violations ? Just admitting the affair would not end their hold on him.
How many years was he married without a hint of scandel? I have a suspicion that the woman supposedly involved is like those women who keep coming out of the woodwork every time the dems want to get rid of a potential enemy.