What do you do if...

Sarah
My best friend just told me she's bisexual. 
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Update :
Okay so she had 2 boyfriends this school year from her last year and this year. Her first one started April 10 and ended 2 weeks ago. She started dating this guy September 9 and like me as her best friend didn't know him because we all have different classes ( I recently got a schedule change so now I have a class with him and the same lunch). So this was before everything happened (the schedule change). I even thought he was cute but once again I never met him. So I'm sitting at my lunch one day and my friend told me that he had a liked him but I was okay with that because I  didn't meet him before. So usually we approve each other's boyfriend like a long test but right when I went to lunch they said there dating but I'm there like "what ????" Because of what we do. So I'm sitting at the lunch table and I keep my mouth closed because I'm not trying to look like a weirdo meany in front of that kid. Okay so during that lunch I kept my mouth closed because what ever came out my mouth then would effect something later. After lunch he comes hug her and I'm thinking oh great. But after having 4days seeing him I see that he is a jerk and I asked people about him and they all said that he's rather annoying,mean, or a kid trying to fit in. Then I told my friend what I think of him (not telling her to break up with him in anyway, shape, or form) but I just didn't like him and I asked my other best friend and my boyfriend and they said they didn't like him. Then later on in the day they said why didn't I approve this and in thinking "what the hell I didn't approve it" and this is when everything starts. People came up to her saying I don't like your boyfriend and you should talk too him and tell him to be nicer. But instead she's tell me and my other best friend that she's bisexual. We are all supporting her and she just broke up with her boy friend and he saying that shes the only one that I love and all that I want you back phrases and now she's confused.
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What do I do