By posting about him you reward his obsession. I'm no psychiatrist, but if he was depressed about the wedding, it was probably through pressure and obligation rather than true love. Then you came along, the angel of his eye, representing all that he was supposed to give up after marriage, and really hammered home for him the desperation and gloom of his situation. In then end, guilt overcame him and he could not continue with that first encounter. He would go on to regret that choice, and that dark cloud poisoned his relationship in a dismal self-fulfilling prophecy until his marriage collaped to a level where he could justify calling you again.
Mind you, he did not call you at random the second time. No, he had been playing the scenario of an encounter with you in his mind over and over since your first meeting. His obsession and fantasy grew with each replay. Your rejection on the second meeting destroyed this fantasy, and he retaliated with the bad review. You know, if it were really that bad, why would he pursue another enounter? Nonetheless, your declining was a good move as you would have never lived up to the expectation level that had been escalating in his mind. It was a no-win situation.
Now he is obsessed with you and tries to torment you. He wants to you to pay for rejecting him, and for poisoning his ill-fated relationship. Be mindful of this root cause, and stop rewarding his behavior.
Don't be angry or frustrated; take a breath, step back and witness the pain beneath his venom. Do not take his malice personally, rather, have compassion for the poor soul who's heart you broke so profoundly years ago.
We do have an anti-stalking posting guideline, but to invoke that you need to stop posting about him and stop replying to him.
We do not consider it stalking when there is back an forth banter until one side finally requests help.