My little dummy was introducing his "new friend" around months before I left him. Literally 2 weeks after I left, he took OW to a party, where he didn't intro her to anyone.
They then concocted a story about how she was consoling Mr. V. about what an adulterous W I was. What a "good friend" OW was being to XH. Oh, yeah, btw, we're now dating.
Meanwhile, I'd lost 30 pounds in 2 months & looked like skelator. So that little stunt at the party where they tried telling people that I was the WW pretty much gave it away.
XH had demanded I protect OW & go along w/that story. People started approaching me w/in days of the party asking if XH was having an A.
I agree w/the other folks who've said it's not your secret to keep. It really isn't. I think that they tend to give themselves away fairly easily, anyhow.
I think if you just state the facts, cleanly and concisely, you look like the BS, not vindictive, or crazy. "I'm sad to say that I'm divorcing Bill b/c of his continued affair w/Mary." That simple.