Talking to Mom/Sister/Unexperienced friends about sex...?

Ok, so I am 18 yrs old. About a yr ago i started to have oral sex and a lot of "dry sex" (not penetrating) and then about 3 months ago I completely lost my virginity. Well, the truth is the guy I lost it to was more of a friend than he was a boyfriend, but I've known him for a long time and I was basically just really curious and I want to know what to do when someone serious comes along. I'm not a whore, lets get that straight right now. I dont know, i guess my curiousity just got the best of me. Anyway, now I don't really know how to break it to anyone. My mom, yeah I'm pretty sure I won't ever tell her... But my sister, well we're best friends but she really thinks im a very good girl and i dont think she would ever expect this of me, and she basically thought I would wait til marriage. So I'm very unsure as to how i should tell her. She's always telling me about her sex life but I definitely have some questions for her that would be nice to be able to ask and talk about. As for my friends, i dont really know how to tell them either. One of them already knows, but she's not a virgin. My two other "close" friends don't know yet, and they're both virgins. I dont know if they would look down on me for my decision. I know it is wrong since we aren't technically in a relationship, but it is MY body and I use definite protection (both the pill and condoms) so please, i dont want to hear any of that bullcrap about me being a bad person or whatever, I know who I am and I know I am not a bad person, its my life.