I don't suppose that there is a way to "get over" missing someone. I suppose that all of us miss someone. When you respect, admire, enjoy spending time with or simply become close to someone, we naturally miss them when they are away.
I'm not sure that there is a simple answer to your question either. I guess it will mostly come down to how we cope with the feelings of missing someone. If you have feelings of despair or depression then you may want to consult a professional to seek help with managing your feelings. Meanwhile, I recommend reading, keeping a hobby or being with friends and moving on with your life.
I'm sorry that you are at a place of wondering how to stop missing someone, I know that it's a terrible feeling but rest assured that you will adjust.