Walloped, I have learned a lot about cheating. Many wives who cheated are angry or resentful STILL even after being caught, even when facing at possibility of divorce. Your wife is saying all the things that a cheating wife wants to save the marriage. She is not doing the right thing yet, but she will, but you will have to guide her. She is too afraid to lose you, so she will wind up doing things that will make it worse. She already has a little. And you are going to sabotage this thing, too, if you don't start getting a grip. You say you are Mr. Calm-Under-Pressure at work, you've got to use that control at home.
I see a lot in your situation with mine. Even live in your neck of the woods.
You are a smart guy, so I think you will be able to understand this. Just about everybody posting here has been through this stuff already, very similar to what you've done, and most of these guys are just as smart or even smarter than you are. My impression is that they know what they are doing, so don't think you are dealing with a bunch of internet yahoos who are bitter, jaded, extreme depressives. They've seen the worst of it, much worse than you've seen, and they are trying to pay if forward for what others have done for them. If you allow them to listen to them, they will have your back and they will show you around the pitfalls.
A short lesson on cheating: It is a human behavior. Like all human behavior, there is part of it that is science and part that is act. Cheating behavior is fairly predictable. The behavior is not uniformly exactly same, but rather there are different types with different behaviors for each type, with some behaviors that are common for all types. If you post on the threads on this forum, you will find these same patterns and behaviors over and over and over and over again. These cheaters may be special unique people, but their cheating behaviors are not at all unique. If you believe "NOT ME, MY WIFE IS DIFFERENT" you are going to find out differently.
Your wife loves you and wants to repent. But she is lying. She is minimizing. She is giving you the trickle truth, telling you a bit of truth at a time. The essential thing about cheating is deceiving and lying. Your wife has been a liar for three months AT LEAST. The sex started three months ago. The "I love yous" started much longer than that, maybe 3-6 months earlier or more.
Yes, your wife was "IN LOVE" with the other man. Why do you think the other man is so "over in heels" over your wife, calling her 14 times to her once? Do you think this 40-plus something guy who is semi-retired a dupe? Do you think this other man who owns million-dollar real estate on the Upper East Side or Upper West Side, do you think he fell so hard because despite your wife was being hesitant? No, your wife was full steam ahead, maybe not initially, not when before she had sex, but definitely she was as hot and heavy for him when the sex started. Why do you think it took 21 minutes to tell other man not to ever talk to him ever again? Why did it take your wife to talk to him 14 straight times for 2 minutes? Why didn't your wife after about 5 calls, just not take the call? She kept talking to other man because she is "in love" with him. Deep feelings. Do you think your wife would have sex with other man on a whim?
What happened to your wife with the other man is that your wife was resentful of you being at work too long and then too much to decompress at home. How I see it, your wife and other man discussed about the wedding, you know how that consumes your whole life while that is in the process. Your wife looked at you, then she looked at other man, and she told other man, "I wish my husband could be like you!" She told other man, "My husband never has time for me, he is not as successful as you, so we have some money, but not like you, and we have to work hard to maintain our lifestyle, and you have done so well for yourself." She told other man, "My husband doesn't care about the wedding, my daughter and I are stressed out, and he doesn't help us at all. I wish my husband was like you." Your wife fed the lines, and that SNAKE used it. This guy probably was a wheeler-dealer at his real estate, and that is a tough racket in Manhattan, he was able to size up your wife, knew exactly what to say. But what is the lie from your wife is the minimization - she jumped right in with both feet and never stopped until you caught her. This is how I see it.
Why do I know she was "in love" with other man? Because your wife was so BRAZEN holding hands walking down the street. The Upper East Side is a neighborhood, there are several little neighborhoods, so are the Upper West Side, so it is not like big bad NYC who nobody knows you, it is the same people walking their dogs, going for a jog at the reservoir, going to the Guggenheim or the Met or MOMA. All of those volunteers from her charity most likely would have spotted them, just like your brother did.
Every cheater lies when first caught, all will hold back, hesitantly, minimize their culpability, not tell you all details (trickle truth), and will calculate using Cheater Math. Cheater Math is where you tell your wife she had sex with other man about 2-3 times, and she really had sex with him 2-3 times A WEEK, so about 30 times. Cheater Math is where she says the affair started about 3 months ago, and when you find out the details from the messages, it actually started in October, with wife somehow now thinking that from October to August is "about" three months. I have never read or heard of a cheater who came clean right off the bat, even when the cheater confessed on her own. Even when confessed, I have never found they told the full truth right away. She was having sex, but the holding hands was open for anyone to see, and she didn't care, she was "I'm in love, I'm in love, and I don't care who knows it!!"
She knows she has to end the affair, but she is hoping she will be able to keep him "as a friend," she may already have told you when you confronted her that "he is just a friend." JUST A FRIEND is one of those universal things a cheater says.
The number one sign of cheating is hiding/guarding the phone. She has been busted, so she will be careful, it will be hard for you to find out if she continues. The number two sign of cheating is her behavior. I sense that her behavior is she is NOT cheating. But she has a deep connection to this other man, so she is not yet out of the woods.
I suspect she is not "in love" with you; for you, she feels "I love you but I'm not in love with you" (ILYBINILWY). She is "in love" (or at least thought she was at the time) of other man. She has a deep connection to you, too, even though I think her romance/sexual side is all on him right now.
When you deal with your wife, pay attention to her ACTIONS. You can listen to her words, but if there is a conflict between words vs. actions, always pay attention to the actions. Cheaters are good liars, plus betrayed spouses can be too wishful for their own goods when the cheaters spin their web of lies.