I've known that I'm bisexual for a few years and I'm so scared to come out to my friends and family.
If you don’t feel ready to come out, you don’t have to. It’s a very personal thing and there’s absolutely no rush. Not coming out doesn’t invalidate your orientation in any way.
Make sure that you’re comfortable with the thought of everyone knowing and that you’ve rehearsed what you’re going to say before you come out. Prepare yourself for people to be shocked, or for them to just completely take it in stride. I hope that your friends and family are as kind and supportive as you deserve, and that they will rightfully not treat you any differently when you do decide to tell them.