I dont wanna lose my boyfriend and he told me hes gonna do the marines to take care of me today?

my boyfriend dropped me off from school today and he told me he wants to take care of me, he kissed me on the forehead and held me for a minute then told me he loves me and that i mean the world to him, he said he wants to do the marines so that he can take care of me. i told him no and begged him not to, when he told me i couldnt change his mind i slapped him in the face and ran inside, i threw my bag down, ignored everything, locked myself in my room and started crying, i ignored all forty seven of his calls and his one hundred some txts, i love him, i dont wanna lose him .im still crying. i want to support him buit im afraid that if i do ill get to comfortable and get a letter one day that i dont ever wanna see adn all thatll be left of him is a flag and the stuffed zebra(my favorite animal he won me at the farmers fair last year(. is there ANY advice i can get from any one? really ill take anything, just please help