I like my best friend’s brother.. Should I go after him?

We’ve known each other since we were toddlers. i dated him when i was 11 for two months and he was my first boyfriend, then i broke up with him cause i said i didn’t like him anymore. then i dated him again this summer (i’m 13 now) for three months then broke up with him to date my current boyfriend. now i’m falling for him again and i have no clue what to do. i’m not really worried about my bff being mad, because she’s always been cool with me and him having a thing. i’m just worried what will happen to our friendship, and i’m worried that the same thing will happen to me and him again. please i need help.