Bestfriend=boyfriend=exboyfrie… and off?

my bestfriend of four years turned into my boyfriend a few months ago. we broke up after a month bc he got into some trouble and it was better off. ever since then we've always been on and off and no matter what we keep coming back to each other. i know we have this attraction to each other and it will always be there bc we both stated that.. but right now i know i fell for him. he's the only person i feel comfortable around and he knows EVERYTHING about me and likewise. he can be a complete but in the end he turns out to be invincible. he jokes with me all the time and is like " i know you love me.." truth is i do; we've dated other people but like i said somehow we always end up together. we come from completely different groups of people but we mesh well in the end. i fell for my best friend... how do i tell him?