Need help!!

Ok so, there’s his boy and he’s my mums besties step son and we’ve gotten a bit close my my mum and her bestie are telling both of us to stay away from him... now he has been a trouble before and been in situations I’m not comfortable with but that was in his past and I don’t think he should be judged for that!!! I just don’t know how to deal with it all.... plus he lost his virginity at 13 so he know last what he’s doing but I haven’t lost mine and now we’re both 17 I feel awkward telling him cause I’ve waited so long, also I think I’m really scared of doing it cause I don’t know what to expect:.. any help would be appreciated, thank you in advance xx