I know the exact way you feel, as I am bi-sexual~
It is difficult, thinking how your friends will react, but your friends know you. And they most likely know your "different" at the least.
This is a sort of mean thought, but no matter what race, if you're gay, white, straight, there is someone out there who will always not like you. (Not you, but you as in people in general) Basically trolls. So don't fear coming out : ) Accept who you are~ There will alway be people out there looking for someone to hate on, simply because they are jealous for your life, and how you were brave enough to express who you are!
In my opinion, especially when one is not sure, before telling your friends, tell your parents/family that you think you may be gay. Letting them know early, helps as it makes then react better if you do end up being gay.
But if you are sure you are bi-sexual, then just tell your friends. If they don't approve of it, they still like you, no matter what they say. If they stop talking to you, then they weren't your real friends in the first place. And if you are not sure that you are bi-sexual, my opinion would be to wait.
I don't mean to scare you, but I am not sure how your boyfriend will act, as I don't know him. He may be surprised, but stay with you. He may think it's hot, as some guys do. Or he may not stay in contact with you. But he will most likely love you for who you are, no matter what!
I hope everything turns out well : ) And good luck~