help me !!! Life Crisis 😩

So i have thsi friend who i used to have a crush on but not so mich dont get me wrong he is still sexy but the problem is that he asked me to be his Bestfriend & i was find with it until he told me what came along with it  , so basically he was like when his girlfriend wont talk to him or mad at him he will talk to his bsfn alot more *wink wink * keep in mind he is sexually active . So idk if i should except offer (im 15 &virgin) im not to aure im ready for this i mean iv had my  share of doing things such as kissin an a little touchy feely with guys but it was never that serous i need some advice please help 😩