Boss finds out you've accepted another job... your play?

[KilgoreTrout]

Got a verbal offer on Tuesday, just waiting for the paperwork to give my formal resignation. I have told no one at my current company about the new job. My boss came from the company I'm going to, so I assume he still has moles there. The new outfit is a $1B division of a $9B firm, so there are lots of potential moles.

So this morning I'm on a conference call and my boss barges in and asks if I have a minute.... I've got my headset on and am following a presentation on webex.... I tell him that I'm on a call. He says he needs to talk to me now.

We go to his office and he says, "I need to have a frank discussion with you. I know you're entertaining a postion with another firm."

Now it's essentially a done deal. I have agreed on compensation and a start date with the new firm, but have not yet received the formal offer in writing. For all I know the offer letter is sitting in a FedEx box on my front porch back home.

So what's the best way to handle this awkward situation? Oh, and btw - I had my review just yesterday.