Should i break up with my boyfriend?? :(?

Am 18 and i love my boyfriend so much that it's ridiculous and its affecting me in various important part of my life, he lives in london but comes to see my once in two months or shoter... normaly he calls me every single day, he doesnt go to sleep without talking to me but now he now i have to beg him to call me and he tells me he is busy with work and friends.. simple things like not speakin to him for one day get me crazy, am not able to concentrate when trying to study and begin to fail simple school test, failing test and him not calling me is just one of the things not affects me, he behaves like he doesn't care abt me and then suddenly he cares then he doesn't care at all again, my heart is very fragile and this kind of unstability gets me depressed, its seriously killing me am soo attached to him because after going through lots of problems and griefing in my family, he was the first person to ever make me smile and happy again and I felt like he was a blessing to me to he gave me back the happieness I lost... now am completely confused cause he makes me happy, then depressed and I know if I break up with him, its going to hurt badly cause my heart is still hurting from previous misfortunes.... help...:'(