I think he understood that the criminal suit (and the civil suits, should he file them) aren't going anywhere. It was a shot in the dark, one of a handful of options at his disposal for intimidating and bullying Kim and anyone who supported her or who criticized him. I do think that he expected it to work as a deterrent. Combined with harassment from his followers, it would be enough to teach his critics a lesson: don't mess with him or he'll destroy you.
Again, I think what he underestimated was how the actions he admitted to would be received, including by many of his supporters. He figured that everyone would agree that Kim's betrayal was the issue, and that his behavior was a family matter and no one else's business. Maybe he felt that, at this point, his patrons owed him their dollars and had to justify ending their support. As he has discovered... that's not how it works.