During my loooong ago college years, a friend of mine from HS went into a cocoon for a year (and came out a butterfly). I'd not seen him for a long time. When I did, he had in tow a close co-worker friend, and she took a liking to me. After she and I hit it off and were socializing, she dropped a few bombs. #1 was that friend had indeed come out and was too scared to tell me himself. #2 was that she found me attractive. MUCH LATER, #3 was that she was bi.
I'd fancied myself intelligent, well-adjusted, tolerant, yada yada yada. But in retrospect, I did a horrible job of dealing with it and my own feelings about her. And my continued friendship with him was waaay clumsy too.
She and I got past it. We had an exclusive relationship that went a few years before other issues killed it. But while that one issue did not kill the relationship, it was still enough to drive me crazy for months early on.
If you and she continue, you may very well have a half year of hell over adjusting to it. Or more. Or maybe only a week. (Heck, for some people, it's a non-issue!?!?) But do NOT assume this will be no big deal. I thought I could handle just about anything and was I ever wrong. Do NOT expect to have this all figured out and sorted out in any neat tidy two week window. (By the way, she probably won't have things figured out so fast either, even if she's sure she did. That she didn't tell you before this raises questions - was she afraid to? - and if she did value time with you, she may well end up second guessing herself.) Not an easy time or easy issue for either of you.
The heart is rarely rational. Good luck with your huge learning moment. (Do NOT crawl into a bottle.)
Bottom line: Are the two of you SO special for each other that the agony of adjustment is worth it? (Isn't it funny, how that's always the real question in relationships?)