It's a process, it will happen (the closure).

I married young so not many ex's, but I was kind of obsessed with a guy who was in no way good for or to me before I met my husband. I was in a self destructive pattern at that time. At the time I thought my life would never be okay because he rejected me. I remember seeing him across a bar with his friends (me with mine) the whole time I was thinking was he looking at me, did he regret treating me badly, I wasn't really fully present with the people I was with because my thoughts were about him - I wanted him to feel bad that night, just as I had. I thought about that when I read about your need for him to see your post. It might or might not be similar to what you were feeling.

Years later I saw him in a supermarket, I was with my husband, our little boy was sitting up in the trolley. He looked from me to the baby to my husband then back again, and his jaw just about hit the floor, he didn't even say hello or acknowledge me other than gawping. All I felt in that moment was amused by the silly expression on his face, this was years later (5) I no longer had any emotional feeling for him.

You will eventually not care either way what he thinks, your feelings will naturally be concerned with other people and he will cease to have any relevance to your life other than a memory not to let anyone use you again.