Who you have relationships with is your own business. I wouldn't randomly approach your friends and say that your bi-sexual. If the opportunity comes up, like talking about relationships and/or sexuality, then you should say it. My friend took this approach at lunch one day. We were talking about sexuality and she admitted that she was bi. I didn't know this and quite frankly I didn't care. I don't have anything against people that aren't heterosexual though.

As for your parents, I don't know. I could just say go for it, but I'm sure that would have no effect on you. Hope you find out what to do and what's best for you. Good luck.