Most Helpful Guy
You cheated on him, and no doubt he feels like he can't trust you anymore. Even if he still loves you, he feels hurt that you cheated on him and broke his trust. No doubt he doesn't even know if you even love him or love him anymore.
Was the cheating accidental or intentional? If you still love him, you will go through some difficult times, but what you're going through probably isn't as hard as what your ex boyfriend is going through.
The only way things will work again is if you really honestly profess your sorrow, guilt, and regret. Only by really being honest with your feelings to him can you have another chance at making the relationship work again. And time can heal what has been broken.