He has smeared his great and honorable career by this affair and his less than honest testimony about the Benghazi attack. The only way he has of redeeming his honor is to testify with the absolute truth of what happened in Benghazi and about any pressure applied to him to by the Obama administration to shade the truth.
The Democrats on the committee will try and destroy him using his affair as ammunition. General Petreaus needs to open his testimony by detailing the history of the affair. This will defange the democrat smear that is coming.
When they have those hearings it should be like one-on-one, not like the last one where you had all of them from the State Dept. sitting together and listening in what the others are testifying to. That way you get a better end result without being intimidated of the others present!!!