I think he's trying to ease his guilt. Living with your lies is very stressful, so confessing can feel liberating.
I'm dropping this because I don't find the ML attractive anymore. I was as invested in him as much as he was showing to be falling for the MC, but he's become too much of a villain for my taste. I need tenderness at this point. I like men who make me feel safe, both in reality and in fiction, and this guy, in this regard, is useless.
How can you have any doubt that this man loves you, he's literally worshipping your body