First off, I want to apologize for calling you a ho. I should have waited for your explanation.

Secondly, you must be completely numb and confused about the entire situation. And pretty soon, the numbness will fade and the anger that's underneath will rear its head. I wonder if you should do the confronting now while you're numb as opposed to when you're angry. I agree that you should leave the emails out of it. You don't want to involve the mutual friend anymore than he/she already is. What did that friend say to your so-called best friend, btw?

Also, when you confront them I think the direct approach is best. Ask if there's anything they want to tell you or talk to you about. See if they're big enough to admit it on their own. If not, tell them flat out that you know what happened and then proceed to rip them new assholes, kick his ass to the curb and then tell her husband.