This is JMO:
They were in their 20s when they met, maybe they were casually dating for a while. Maybe it was easy for him to hide what a controlling monster he really was for those years. People can do that. Think about your own relationships with coworkers, you show them one side of you (professional, polite, etc.) even if that is not your true personality. He clearly was able to trick her into thinking he was a guy worth marrying. He was a handsome guy, he's in med school, etc. on paper back then, he looks the part of "successful man you want to marry." After all, that's what your supposed to do, go to college, get a job, meet a partner and get married and have kids. That's the playbook.
But clearly, once they started to live together, once she moved to VA and he was in residency, she began to see a side of him that was not acceptable. The rumor is he was controlling and abusive, emotionally at the least. When you are young, you can find yourself in those types of relationships and it takes courage and maturity to leave. So, she left. The rumor is she had to "escape" meaning her family had to come rescue her with a U-Haul when he was at work. The rescue is a success and she goes back to Columbus to start a new life, but now she has done something he considers to be a blow to his ego and his pride. Being the narcissistic controlling egocentric monster that he is, getting "abandoned" like that is going to burn him. He's going to focus on that and not be able to let it go. During the divorce the rumor is he threatened to "always be in her life" and to "buy the house next door" so now that is his mission.
As the years go by, his apparent lack of social skills would catch up to him at work, in dating, socially. He has his career but I bet he did not have much beyond that. Limited friend, limited partners, certainly no one like Monique who was beautiful, radiant, special. So as he's approaching 40 where is he? He has no spouse. He has no family. His prospects are dwindling. He is potentially struggling at work and having trouble with the boards plus facing a malpractice lawsuit. A lot is piling up on him. He is starting to feel like a real loser. Meanwhile, the Tepes are picture perfect. Anytime he wants he can pull up YT and go watch her happiness. Each time he watched that video would be an ego death. Seeing the perfect family with perfect beautiful kids from afar would be salt in the wound. For him, those should be his kids, his house, his life. He's incapable of blaming himself so he must blame her. Fast forward to holidays 2025.. it's cold, it's depressing, he still has nothing, everyone finds him odd at work and socially, he is now so far gone he has given up hope. Like an incel who has taken the black pill or whatever. He snaps and decides to do the one thing he can do to ruin her life and settle the score from 2017 in VA....