Sounds like you are doing very well. I especially like what's going on with the kids. That's great.
Two things: First, about mysterious. The several episodes you listed sound like you are having an affair. If it comes across that way to me, it very easily could to her, especially since that's her mindset at the moment. I've never been a real advocate of fake mystery. If you were actually separated, I'd say, "keep so busy that she can't always get ahold of you", but because you are living in the same house and she sees your comings and goings, any "mysterious" and vague, "I'm going out" or "I'll be late for dinner" sound like cheating, especially since you are apparently so happy at the moment, despite the fact she dropped a bomb. I personally would tone down on the mystery.
The second thing: Are you fitting this GAL, etc, into a favorable time? I know the focus should be on yourself, largely, but you should still consider your wife's feelings. Meaning, I hope you aren't leaving her all the activity that seems to come before and after dinnertime while you are at the gym. If so, it will seem very selfish. You don't want her resenting you because you took off right before or after dinner.
Third thing (sorry, couldn't help myself): I'm sure you are doing this, but just a reminder that you can still be nice. If you haven't asked her any questions about work or her life, it's okay to do so, and you can then show her how well you listen. I just mention this because sometimes a person gets so successful at detaching, and so good at getting a life, that it comes across as a person that is self-centered and couldn't give a rip that the marriage is breaking down. You can, and should, give her attention, but only as much as she's willing to accept. If she rebuffs any attempt to engage her in conversation, then it's not the right time.
Well, good luck.
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt
