I know it does take time for you to get over it totally. However, I have concrete suggestions for how to get over your first love TODAY. By saying that I mean to not overthink of him/her and live a peaceful life.
First of all, understand that this is not the end of your dating and future relationship. You will find love again. Have your friends and families know of your true feelings. They will help you get over the first love, they understand the struggle. But they do find the new one true love in their lifetime, eventually.
Prepare to endure the oncoming pain and feeling of loneliness. Time will heal your pain. Don’t succumb to that weakness. Whatever you do, do not hook up with your ex. You are not helping yourself. Know that it’s alright to cry. It helps to release all the pent up emotions. Just let it out, it will make you feel better. Have a nice conversation with a friend afterwards to help you get by.
Take good care of yourself. You might have difficulty sleeping, or finding yourself awake at night. The loneliest time is when everyone is asleep. Exercise during the day, exhaustion helps you sleep easier. The extra physical activity will also reduce your depression and makes for a good distraction.