Prior Navy prosecutor and defense counsel. Standard caveat - no one on this forum, including me, can give you legal advice on what to do in your particular case. We can talk to you about the process and general rules, but please don't take this as legal advice from your attorney. As someone else mentioned, Soldier's Counsel can help you out if you want real advice. Or you can hire a civilian.
That said,
@RonG and
@chaplaincharlie are spot on (both here and in your other parallel post). Article 2 absolutely allows any retiree (length of service, TERA, TDRL, or PDRL) to be recalled from retirement to stand court martial. As
@Jason Perry said in another post, it's stupid rare. Almost never happens.
It may ease some of your fears to know a few things about the potential charges of Adultery and Fraternization. They are a little more nuanced than a lot of people in the military think.
First, adultery is a crime under Article 134 of the UCMJ. Article 134 is the oddball of the UCMJ. It encompasses a lot of different types of misconduct (from drunk and disorderly to assault with an intent to commit murder). All of them have one thing in common, called the "terminal element." The terminal element is that the conduct must have been either (a) prejudicial to good order and discipline, or (b) of a nature to bring discredit upon the armed services.
It's not enough for someone to just sleep with a person who's married to someone else. The government also has to prove, beyond a reasonable doubt, that the conduct was detrimental to good order and discipline or that it was service discrediting. That's hard to do in the case of a discreet, one-time thing between members of different commands who didn't know each other. The Manual for Courts Martial lists a number of factors that a jury should consider when deciding whether an affair meets that terminal element. The list includes things like the ranks of the people involved, but also things like whether the conduct continued in spite of command warnings to stop, and whether government time or resources were misused to carry out the affair, and the impact of the misconduct on the participants' abilities to support their military missions. The UCMJ describes prejudice to good order and discipline as "an obvious and measurably divisive effect on unit or organization discipline, morale, or cohesion, or is clearly detrimental to the authority or stature of or
respect toward a servicemember." It's not nothing.
There's also a defense of "reasonable mistake of fact." Basically, if the accused can show any evidence that he didn't know she was married, the government has to prove beyond a reasonable doubt that he's either lying or that his belief was unreasonable. That's hard to prove.
Fraternization is another Article 134 offence, which means it has the same terminal element requirements as Adultery. The mistake of fact defense is even stronger with Frat, though. Here are the elements of the charge:
(1) That the accused was a commissioned or warrant officer;
(2) That the accused fraternized on terms of military equality with one or more certain enlisted member(s) in a certain manner;
(3) That the accused then knew the person(s) to be (an) enlisted member(s);
(4) That such fraternization violated the custom of the accused’s service that officers shall not fraternize with enlisted members on terms of military equality; and
(5) That, under the circumstances, the conduct of the accused was to the prejudice of good order and discipline in the armed forces or was of a nature to bring discredit upon the armed forces.
Element 3 means that, whether the accused says anything or not, the government has to prove beyond a reasonable doubt that he knew she was enlisted at the time of the action. For a normal Frat charge (Department Head sleeping with a Boot), that's not hard. Everyone works together and wears uniforms all the time. But for a random girl some guy met at a party? That's a different story.
If you were still on Active Duty and I were advising your command on this, I'd tell them not to bring any charges. First, because they would be very difficult to prove. Second, because these are piddly little charges that we'd never take to a Court Martial anyway. These are Article 15 charges, at best. You almost always get Courts Martial for Adultery or Frat as an add-on charge to more serious misconduct like sexual assault. And you don't (read: can't) be recalled to Active Duty for Article 15.