Walloped, I think my wife's affair was similar to your wife's in many respects. From what I can see, both were very emotionally intense. Both of our wives have claimed not to make any contact after d-day. I don't believe my wife. I have no evidence. I did not intend to polygraph. But knowing how deeply my wife was involved, and having seen so many similar posts, I cannot believe my wife never contacted the guy. I don't believe your wife didn't contact him, either. I think they said their goodbyes. I think they have no intention to ever contact them again. I can live with that.
I did not ask for a timeline because I had seen all messages. My wife tried to delete, but she screwed it up, so when I found out, they were all still there. This was a good thing, because I could see the entire breadth of what was going on in there relationship. My wife did not say anything bad to me in any of the messages. Pretty much, it was like I was invisible. Other man either did not mention me, or her wife. The only references to me or his wife were things messaged like "my husband is going with the boys to play ball, we can talk at 7 pm" or "I had to hang up because I lost my privacy." I know my wife well enough, so I could tell from the messages that she was really in deep. From your posts, I can see that your wife was really in deep.
If your wife was going to contact other guy, that would have happened in the first couple of days. I assume she could have done it at SIL's computer or phone and she did. I don't think she has any intention to ever want to deal with the guy again. Just based on my wife seeming similar to yours and what you've posted.
Did she love him? I believe absolutely, she thought so. Now she probably realizes it was infatuation. The messages between my wife and other guy was very superficial, not sharing deep secrets between each other, yet I could see my wife was so wrapped up with this other guy. Complimenting each other about a third of the time, believe it or not actually fishing for compliments for themselves if they went too long a period without receiving one - so yes, I do believe the ego kibbles has a big part of it.
About three quarters of my wife's compliments were about how virtuous the other man was. "Oh, OM Name, you are so honorable, I trust you so much in what you say." Cheating on his wife, but she thinks he was "honorable." So I don't know about your wife, but mine was not thinking AT ALL analytically or logically, she was just going with the flow and the flow was just compliments, how much they love each other, and sex talk. Besides the compliments, the other main subjects were how much they loved each other, and sex. My wife did initiate probably about a third of the time re: the sex talk, probably two thirds of the time re: the "in love" stuff. The other guy gave the "in love" talk only when he wanted sex talk, my wife initiated the sex talk just because she knew he liked it, not that she didn't enjoy it, too.
Overall, it was all just a house of cards, all of this intensity talk back and forth was just superficial stuff to anyone who would read this objectively. It was high school crush stuff, not even, except for the sex stuff, I might be thinking it was like what you might think between two 7th graders. I did not search out for a forum for a while, so I didn't know, but this is just the large amount of messages between cheaters, just very childish and juvenile. Maybe about a month in, I was reading and re-reading it some of the stuff, and not comprehending how someone in their 40s who I know is a mature adult, be so juvenile. My wife didn't remember it that way. So I showed her one and told her to read it out loud to me. Then another, and another, and another. I think that helped her, to see how ridiculous she sounded.
Have you been able to read much of their communications? If not, can you get some of those messages? It might help you a little.
I think your wife is doing OK, but she's not there yet, already. I think she still has some lies she hasn't told you yet. When you ask her about the stuff like how did they get her new phone number, I felt like she was running around in her head trying to figure out what part of the lie have you just found out. Like I said, I do think she contacted other man or vice versa. You may never know, but I know my wife, and she has a pretty good memory, she would know who she gave the phone numbers and who didn't.
In aftermath of d-day, my wife did not talk to other people, I think she was afraid I would suspect, even if I was wrong. I was at a hair-trigger to divorce and I had told my wife if I even suspected the first time she would find out about it is when she got filed for the divorce. Which is probably the wrong way for me to go about it, but that's what I did. My wife asked me at the time, "so if I do nothing wrong but you incorrectly assume the worst, then will you divorce me? That doesn't seem fair, it's really beyond my control how you act," and I said, "yes, I will divorce you if I even suspect, so you better not make me suspicious, and yes, it's not fair, but I don't think the cheating was fair, either, and your cheating was completely beyond my control, and at least I'm warning you, which you never gave me a warning before you cheated."
My point is, I guess, is not to worry too much to be "fair" to your wife as far as her behavior. If she is doing anything to make you feel anxious, let her know and expect her to do what she can to alleviate it.