But that more importantly she wants to make the choice to "turn her back on him and thoughts of him." That may not be the ultimate goal of indifference but it's a good start to make that effort.
She does need to make that choice on her own -- no one wants the ghost of AP haunting a relationship.
My wife kept her A secret for years and years before confessing. The only upside to that is she did make the choice to tell him no, to end it, and to get 'over' any feelings she had or thought she had. Without counseling or any telling anyone else, she said it took her about two years to be done with any feelings about or for him. It didn't help AP called a few times to make sure she was done.
The one thing she didn't know when she confessed is that AP never kept the secret, had thrown her under the bus years before. It cost her a promotion at the company they worked at.
So, in our case, she had to get over anger at AP first, then get back to indifference.
After counseling, my wife realized her feelings were invested in the escape, in the fantasy of it all and not really AP at all.
It all takes time and none of it's fun.
But don't bottle up the seemingly endless questions. Set a time aside where you both can talk about what each of you need to say.
Infidelity is more than trauma, it literally shifts your reality of what you thought your life was. That's why the questions, sometime the same exact questions, keep popping up over and over again as you try to reset what really happened while trying to see what you NEED to happen now.