Need to talk to a girl about something?

Last week on Thursday, I talked to this girl about going out sometime she agreed but I never really put like a time or anything. So today I approached her to ask her out to the movies, she looked at her friend, as told her to tell me, I didn't know what she was talking, then she's tells me that she's bisexual and her friend is her girlfriend. At that moment, in my head I'm like "oh ****" and then I akwardly said "oh.....kay" and walked away. Thing is, last Thursday she agreed, to go out sometime and didn't mention any of what I typed above. So I'm thinking tomorrow, going up to her and call b.s on her being bi, I just don't believe and I would of rather like a yes or no, answer than a lie. But if she is then, ****.

I also talked to one of her friends, he said that he didn't know, and acted all surprised about. I don't if I can gather anything from that. Don't answer, that it could be a three way that is ridiculous.