I am saying that telling a third person you are going to write a blog about XYZ is as defamatory as writing the blog about XYZ, if the XYZ you tell this third person you are going to write is false and defamatory. And, if what the third person UNDERSTANDS the comments to mean can make the comments defamatory, even if what was said was not meant to imply anything defamatory.
If YAG says to a third person that he is going to write that quincy molests koala bears, it says to this third person that YAG has some unrevealed information to support his belief that quincy molests koala bears. It would be defamation even if YAG never writes about quincy in a blog (or posts it for all to read on FreeAdvice). He has already defamed quincy to this third person. Accusing someone falsely of molesting koala bears, or implying falsely that someone molested koala bears, could also be determined by the court to be per se defamation, and quincy could collect damages on this presumed injury.
If, however, YAG tells this third person that he believes quincy molests koala bears because he found a koala bear hair on quincy's suit, YAG MAY be able to successfully use opinion as a defense to a defamation action. He may be drawing the wrong conclusion from the existence of koala hair, but the hair could support the erroneous conclusion which is the basis for YAG's opinion. It would be up to a court to decide if YAG's comment was opinion or not.
(. . . . and, as a note, it was consensual, the koala bear was of legal age, and I am confident she will remain silent about the whole matter, anyway. . . .)
But your example, "I am going to kill my wife" equals murder, is a whole different animal than what we are speaking of here. It is not defamatory (although it could equal a threat to commit murder and get the speaker in trouble). Saying to a third person that "I am going to write a blog and tell everyone that my wife committed murder" would be defamatory if false, however - you are implying to that third person that your wife is a murderer.
So, in other words, there is no "conspiracy to defame" here. There is defamation as soon as the defamatory comments are communicated to a third person. The consultant communicated his defamatory comments by describing to the contractor what he intended to write about the company's financial health.