A philosopher said that hate is not the opposite of love. hating your ex doesn't mean that you don't love him anymore. The fact that you're giving him such intense emotions means that he has an effect on you and he is still worth your attention.
Apathy is the opposite of love. You can only say you've fallen out of love when you no longer care what he says or does.
So, how can you stop love? Unfortunately, you can't. Love dies on its own. you'd just wake up one day and realize you're over him. Don't suppress and it will come naturally.