It's the only way out for her. She knows the Fonger is wounded and the jackals are circling. She's got enough street smarts to figure that out...
Kim has some street smarts, but in any sophisticated sort of way. If she did, she'd never have sent that email and she'd never have wavered on the truth. The truth puts her in a better light than her lies and manipulations have. A calm woman quietly telling the truth with her head held high would have been a better image than that which she has presented thus far.
If you've read Kim's letter to the public relations group in NY, you can see that she is not an uneducated guttersnipe. Her grammar, punctuation, vocabulary and sentence structure are quite good. She didn't need to go down the road of acting and looking like trash. That was a mistake and it wasn't "smart." She's obviously trying to rehabilitate that image. That IS smart.