WCF....I've been reading your posts, but never written to you before. All I can say is Wow!! I can't believe she would say that to you and be so nasty when she is the one sleeping with another guy....WTF!
Anyway, I think the advice you've gotten is the right approach. If it were me and my W was doing that and speaking like that then I would just reiterate your LRT letter, state you won't nothing to do with her if she is to continue doing this, tell her you wish her all the best and then say a final good bye and let her go.
Don't call her, don't take her calls, texts or emails until she falls flat on her face and realises what she's done....which based on what you've said about her she probably will one day...although it may be all too late.
Take it easy


M 35
W 31
Separated 2/2011 but still together
Ended it 4/2011
Together 8 yrs
Married 3.5 yrs
Lawyers involved 6/2011