UCMJ adultry question?

I have a really good friend who just confided in me that she had cheated on her husband when they were going through a divorce. They ended up working things out and she admitted her wrong doings to her husband. The complication comes when, the co-actor is army reserve. she is Air force reserve and the husband is active duty army. The co-actor is pissed and wants to tell the chain of command about the wife's wrong doings. He does have photographs, so there is proof. BUT the threatened her with "either give me 3grand tonight by midnight or I will tell." which is exthorsion. She has text messages. This is all a huge mess. She and her husband have made peace with this issue but this guy is trying to stir up trouble. any thoughts on what can happen to her?