Blackmail is a form of extortion. If it were true that extortion required violence or destruction (it does not) then so would blackmail.

I’m not exactly what you mean when you say that “criminal blackmail excludes legal process,” but if you mean that threatening to go to the police with evidence of a crime if the criminal does not give you something of value, you are absolutely mistaken.

Threatening to go to the police without seeking something of value for your silence is certainly legal, but the moment you try to sell your silence you’re going to be wandering around in the vicinity of extortion.

> “criminal blackmail excludes legal process,”

They're saying that "If you don't pay me $X, I'll tell your wife I slept with you" is not illegal, so it doesn't constitute criminal blackmail.

I’d probably run that assertion by a lawyer before I lived by it.

Pay me or I will ruin your reputation is very much blackmail. Investigative journalism would become potentially extremely profitable if it wasn't.

Of course it's blackmail. The question is if it's criminal or not.

Blackmail is a crime, so this would be a pretty safe bet.