Long distance relationship. Guide me!

I've known my boyfriend for 10 months & then later we came into relationship. It's been 3 months of our relationship & now he's shifting to USA with his family for his further education. I am a very clingy person. I need lots of time & attention. And the fact is that when he will go there he will be too much occupied with work, studies & family. He won't be able to give me much time. I just keep on crying thinking about it all day long. I am not able to concentrate on any work. I can't stop thinking about him. We had conversation about it. He assured he will try his best to give m time. But still the distance thing is not letting me be at peace. It is affecting my mental & physical health. I am having my final exams and he is going at that time only. I don't know how I will cope up. We both love each other but sometimes we fight like enemies. I don't want this relationship to end. I don't want him to get fed up of me. Please guide me