I honestly don't think there is anything she's holding back, what I know is backed by their texts and I believe if it went further it would be discussed. If we want to be explicit, it went as far as his hand in my wife's knickers for a few seconds. Kind of a grey area and probably something I can get over. She left after few seconds and the messages back this up actually.
First of all, there is nothing "grey" about a man putting his hands in your wife's private area while they are alone in a car.
Sometimes it helps (or hurts) to really think these things through and break them down.
- How did this man get access to her vaginal area? Was it accidental? Did she have no idea his hands were near her vagina? Maybe he got halfway there before without complaint and decided she was ready this time?
- Why would he think he could "go there"? Wouldn't there be a lot of "activity" in order to prep for this step? She didn't see this coming, particularly with all the texting etc. that preceded this incident?
- Did he force himself on her? Like pry her legs open? Or did she put herself in a position for this to happen then maybe had second thoughts?
- Where else has he "been" with your wife? (She is almost certainly minimizing in this respect)
- What about her? It sounds like she is passive and he just "did stuff". I don't believe that. She was an active participant. What did she "do to him" physically or otherwise to encourage this activity?
And so on.
Some people will tell you this is too nitty-gritty and unnecessary torturing your wife or yourself. I disagree, even though it is torturous.
The reason I disagree is that cheaters like to gloss over the real story so they look better: "He jammed his pants in my knickers and I shut it down!"
What they neglect to mention is the grinding, touching, deep kissing, maybe her touching him intimately, maybe acts that did not involve hands at all, perhaps a number of "buildup sessions" prior to that etc. Maybe above the belt was okay for her.
They skip past what really happened and make themselves into a mini-hero. He tried to get in my pants and I stopped it because I am not that kind of girl!
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It may all be too much for you, and as someone posted above, if you are comfortable with the "summary of events" with your wife leaving out just how active of a participant she was in all of this, then that is your prerogative.
But in my opinion, it lets the cheater off the hook for the hundreds of decisions, lies, plans they made, and actions they undertook to get them to the point where some dude believed she was cool with his hands in her pants (or whatever really happened) and they don't face what they really did, which is not just a session in a car, but a period of planned and executed betrayals without and care for you.
The reason they gloss over the details and timeline is they don't want to think of themselves as "that type of person". When they face "what they actually did" they have to admit they are that type of person, and if they truly want to be better, they have to deal with the whole landscape of that behavior, and not localize it to one incident.
And in the process of dealing with it, they have to risk losing "what they want" which is to stay married to you, even though they created that risk over time and with complete intention.
In my opinion, they put so much effort into betrayal and deceit they need show at least as much effort to truth and building trust.