My wife finally opened up on this. The truth carries threat of pain with it, so beware if you are really seeking to know.
I found out that my wife, who had a six month affair with her ex-gf of 14 years described feeling "awkward" at first (and as she spoke, I warned her that is a horrible trigger word now), but after a few visits she felt the comfort that their familiarity gave them. This aspect is very painful for me, because my fear had been since discovery that they still had a connection, feelings, or unfinished business. She said there were no wild emotions or feelings, no "love" or romantic feelings, but it was a nice feeling to be with someone familiar with whom you felt no responsibility. (We had been together longer than they had at this time!) Ouch!
She also confessed that because she always had alcohol when they were together, that is why she would grab a beer the minute she walked in the door. This is the first time she confessed to doing something so deliberately deceitful to cover her tracks.
She said her ex asked once if they could get a room so my wife didn't have to go home. My wife told her -- and said she always maintained -- that was totally out of the question. She did say that her ex would often say she wished my wife didn't have to leave (when it was time to come home so I would not have suspicions if she stayed away longer than her "cover activity" called for.) I believe her ex missed her and wanted to pretend her way back into her life.
I left the door open for my wife to tell me more. I have let her know that she did not love me the same during her A, because I could feel that. I have asked how much she resented me during that time, but her non-answer tells me it will take her some time to think that about before she gives me the truth.
It wasn't excitement, although I am sure their first few rounds of in person visits held some kind of excitement until it became familiar. My wife did say that one day why touched, unexpectedly, an arm or shoulder, and that something in her responded. Ouch! But my wife also said about half or two-thirds of the way through the affair it started to become a bit of a drag, as the newness wore off and the old familiar started to remind her why they were not good together. Why she did not break it off then I will never know.
And yes, my wife says in one of their last times together she said something that hurt her ex's feelings. Tears led to my wife cuddling her to comfort her on a bed in her ex's sisters house (she was house sitting), but my wife said that her ex threw her leg over my wife's leg, and that ended the cuddle session real quick. My wife said she got up and said "That is not yours." She said that was one of the few times I came to mind, as the intertwined legs was something she associated with me alone. They left the house and went to a park . . . but it was not enough for my wife to just come home to me. That was also the last time my wife gave her money . . . $500 cash. I guess she also told her ex this would be the last time she could help her out financially.
I have asked her what was in her mind while driving to and from . . . haven't gotten that confession yet. My fear is that some of the time she was actually glad to be leaving this house that she so associated with the stresses she was trying to escape . . . and that hurts. Because I was stuck here, ill and unable to get out much at all that summer. She says she often arrived at ex's house (a 45 mile drive in the worst congested traffic in the area) in a grumpy mood, but that never prevented her from driving that 90 mile round trip to be with her ex for a couple of hours. Only one time in over half a dozen trips there she left her ex early to go do what she told me she was doing . . . kayaking. She didn't leave because of me, she left because she would rather be on the water than hanging with her ex that particular day.
If you are new and reading this, I am at 2 1/2 years post d-day, with a spouse who took over a year to even begin to show anything hopefully like remorse. TT went on over a year, and she still can get a little defensive when I get close to something she is afraid to tell me. She has turned another corner, but I have said that before. Progress is neither linear nor level: it is a roller-coaster with no brakes and it is messy. Listen to your gut and do not let go of what you need.