i need help.

okay so, this random number facetimes me in the middle of the night. over and over. i didn't answer but i gave the number to my boyfriend. he called and the person said i was cheating on him(when in fact that is wrong). i love this man with all my heart. i wanna be the one he marries and i wanna have his children some day.

i need some advice on what to do. my boyfriend doesn't know what to believe and he might leave me because of this random caller... please give me any advice