You do wish this hadn't happened, but it's water under the bridge, and obviously the fact that they are going to start dating is going to mean that all of your other friends will also know that she cuckolds you -- and you wouldn't be at all surprised if several of them will want to start a relationship with her too.
I need some time alone with him. Go down to the bar in the lobby. I'll call you when we're done.
Your wife is making it clear to you that if you truly love her -- which you both know you do -- you will step aside to give her and your best friend the time and privacy they need to explore their feelings for each other.