He was no doubt told “Resign, or lose your Rank, face Court-Martial, and/or lose your pension”....easy pickin’s.
No. A retired officer of the United States (as are all military officers) can be stripped of rank and pension only if he faces a general court martial, is found guilty under the UCMJ, and is then dismissed from the service. Even Obama isn't crazy enough to court martial Petraeus, for then every bit of dirty laundry would become public. We'll see tomorrow how honorable a man is Petraeus.