My ex cannot get out of my head.
That's awful. What do you mean you can't get him out of your head?
I can't stop thinking about him, it's ruling my life.
I understand that it can be hard to move past a relationship but it is bad to dwell on the past. Getting stuck in the past will leave you feeling miserable.
I think I should confront him about it.
But if you do then you will be dwelling in the past and then you will have a hard time moving on. Just leave it alone and you will be happier for it.