Oh I'm sorry, you asked for Sage advice, not back-handed advice.
First thing is realize that even if you think you can love multiple people, (which I'd argue you can't because if you loved your wife, you'd know this is going to hurt her, but that's another conversation) your wife didn't marry you so you could love her and whoever else happens to come along. Just like I imagine if your wife could love multiple people at once, you didn't marry her for her to love you and anyone else that she might fancy.
So, I'd confess that affair. Because it will be better coming from you than someone else.
Second piece of advice, since this was a coworker affair (if my memory is right), you're probably going to get fired. Maybe you'll be allowed to resign if you're highly placed in a company, but yea, you're in trouble at work. So I'd suggest working on that resume, and sending it out. Because you'll be needing a new job.
And this will help show your wife that maybe you are trying to actually help the marriage, and not look out for your own interest. Then once you stop acting like a teenage boy wanting to boink everything you see, you'll realize this was a good move and how stupid you were to do this.
Last piece of advice...you better start a budget, and cook, and start saving. Because if your wife decides to divorce, and since you'll be losing your job, you'll be paying her attorney fees, your attorney fees, plus the other bills, like the mortgage, I assume you want to keep the health insurance, the auto insurance, car payments...
And just think! You could have avoided all this if you had listened to the forum the first time! Don't feel bad though, I wasn't very good at listening when I came here either.