I am a bit confused, you say all your friends already know that you're bi.
So why are you scared of the reactions if they were already told?
Unless if you mean "They know, but not through you. And you worry about how they'll react the next time you see them".
If that's the case (I'll assume it is for now, otherwise I have no idea what you're even asking), I will note my advice is limited because I don't know your friends personally so I have to go on a 'on average for 8-9th graders' assumption rather than predict specific people.
So with that assumption made, I would expect a few jokes and trolling by your friends to be made about your sexuality. But I doubt you're going to get shunned or actually end up having friends being hostile. Mainly because if they were going to react badly, you probably would have already known cause they would felt some need to freak out at you through text or something.
Cpt Toellner said
My god, I really want to agree with this post, but times have changed code, we actually kind of give out advice now. Unless they are a mutually hated person in spam, any hostile post here would be seen as taboo.
[2] Basically what I was gonna say.
Like if say I asked for advice in spam, I'd probably have some people offer help but also have a lot of people going "Fuck you, we don't want you here".
But someone who isn't as unpopular would probably get more support than trolling.