you are addicted to him. it happens in relationships. especially after a divorce from a spouse that left you emotionally starving for affection. I went through it too after my divorce.
On the day you wake up and realize that when you see him, you feel absolutely nothing, like he's just another human walking down the street, like you are totally detached from any emotions for him, that when you see him with this other lady, you'll actually start laughing to yourself knowing what she's in for in the long run, you will then feel liberated and alive again.