Can anyone give me guy advise ?

well i think i kinda like this guy && i no he likes me because he keeps askin me to be his girlfriend && hes even bought me stuff. well its my bestfriends brother && shes cool with us goin out she dont care but the only thing im worried about is that i dont like anyone knowin about my relationships well atleast parents and i dont think my mom would be cool with it and it would just be weird in front of his parents because i grew up with there family i just dont no what to do about that !