It seemed liked people were a bit wrong about Leanna. Sure, she was a bit naive to follow Phil, basically getting kidnapped to Washington State far away from her family. But seeing Phil now falling apart since she left shows me that she gave him some positive influence in his life. Not that much, but enough for Phil to not go off the rails completely. That does not excuse her obnoxious behaviour and being a bitch from time to time (see the Kingdom Hearts stream chat incident).
Having a (full-time) girlfriend boosted Phil's ego because that set him apart from almost all of his fans. Leanna was his trophy, much like the BMW and the adult house are, and replaced his figurine and statue collection. He used her to show that he was something better than his fans, telling them what it means to live in a relation (though he did his best to ruin said relation without leaving his "office") and basically to have the moral high ground. After all, what do virgins know about relationship with a real women, he must have thought.
With her leaving him she wrecked him, there was no need for shit-flinging on social media about him. Every day since she left he shows her what a mess he has become, his health, shape and Business going downward in almost no time. He had no social skills to begin with and is now a hermit, disconnecting himself with the outside world because he refuses to get his shit together. Not getting a job, not selling the house, not meeting people, not attending the doctors (he will blame the detractors for all of that).