Trevor told Jonny Robb to stop posting about his behavior towards women, and in exchange he would give him $500,000. He told Jonny to come and collect $50,000, and that $50,000 would be paid in successive increments as long as he continued not to post. When Jonny arrived to meet Trevor he found that Trevor was with the police and it was a sting operation. He was arrested for extortion and possession of a controlled substance (weed + mushrooms in his car). When he was released from jail he took his own life. It's not 100% certain that Trevor first brought up the idea of a payment to keep him quiet, but that is my belief after talking to Jonny's family and friends as well as listening to Trevor's story in person.