I am a BS and will try to be gentle.
The title of your post is a bit confusing (disturbing) to me.
Maybe it's my own preconceived notion but the term "Dredging" as used in the phrase "dredging up the past" has negative connotations. It is a term that is generally used when someone brings up something from the past that they should probably be over by now. If I am mistaken then please let me know. Or disregard my post.
Your wife's world was destroyed by you about two weeks ago when you revealed your affairs. (I am basing this on your other post when you said you finally revealed the truth in early april--don't know if there was trickle truth or gaslighting)
But now that she nows the "truth" she has to make sense of her life, and the utter destruction of her marriage.
When she asks questions....if you take the attitude that she is dredging up the past or that she should be over this by now...then R is never going to work...ever.
She is still trying to make sense of why her world was destroyed. She's gonna have a lot of questions, your answers are going to cause her pain and more questions. She's going to go over the same questions and answers over and over. It's part of dealing with the trauma. It is going to be uncomfortable. To be frank, you should be thrilled that she is even giving you the chance to talk about these things instead of just packing her bags and moving on.
I don't particularly mean to be harsh here, but please read some of the healing library articles, particularly Joseph's letter. It should help a bit.
Good luck, hang in there..you are about three weeks into a very long process. And it's gonna be bumpy.
And don't get hung up about things like
We seem to make some progress and then more questions and backwards we go.
It's been just over two weeks since her DDAY...how much progress do you expect her to have made?