Misserable...

Your mind and your heart can completely disagree with each other. Even if your mind says "stop", your heart can still say "go".
Trying to force your heart to stop loving someone is pointless and it might even make it hurt more.

The heart itself is impossible to control and is unpredictable. Maybe your heart will fall high over heels in love with another guy already next month. You never know.

Your mind and heart will have to work together to move on. If you think about him (too much), you will only remind your heart that you're heartbroken. Something you should do is try to keep your mind on something else, whether it's a pet, friends, hobbies etc. While your mind is busy thinking about other things, your heart can recover from the heartbreak peacefully.

Support from friends and family is always good. Having your loved ones supporting you through a heartbreak can help you focus and help your heart recover faster. You know, to "fill the hole" in your heart.

One important thing you should think about is not trying to rush things. The more you love someone, the harder it is to let go. You need to take one step at the time. If you think you can't do it alone, you should turn to a loved one for help.
(( Quote: "You'll move on and be a champion in your next endeavor as you did in your past ... Life is not a success-only journey. You are going to get beat up along the way." - Dr Philip "Phil" McGraw, one of the world's best psychologists )).

I hope my answer helped a bit or at least made some sense and I wish you good luck.
If you need someone to talk with and your friends or family members are busy, we're all ears.