Teeenage life, best friends confesses she's bi

So, I'm 15 and I'm a freshment in high school, and everything i changing now- I feel like nothing connects me to the person I was before, I started to have different thoughts (which some sometimes surprise or scare me a little), different feeling wishes and aims in everything I do, and I feel like I'm finding myself, and that unknowledge and the unknown world or growing up I became a part of scares me a little bit I gotta confess, and confuses me a lot. I don't really like unknowledge, especially about myself..and my loved ones. See, my best friend (also 15) who I've known and hung out every day since we were six, this year for the first time doesnt go in same class, not even in same school with me, but we stayed really close and it helps that we live next door. She is one of the most sweetest and kindest and amazing people I've ever met, with such a big heart, and I love her very much. But, we now started to hang with different people and circles and shes also experimenting and trying to find herself, and it's really a confusing and weird time for us all. Now, all of a sudden in 1am, slowly she admitted to me (over a text, we'r texting now) she has these feelings for this person, and as I assumed it's a boy, it was a bit of a shock when she sais it's a female person. She confessed me she had discovered she's bi, and I of course instantly said that I think it's great and totally understand her, it is normal, and when I asked her if she's sure she explained to me the feelings she feels when she's by that girl the butterflies and how seeing her makes her day and they almost kissed on one party, which made her so happy.. Now of course I completely approve and think everything I said, but the truth is, I am kind if shocked that this is happening and am not sure how to deal with her, and help her, since I know I'm straight and it's really weird to give her advices about girls.. My rule has always been the heart wants what it wants, we are all humans, but the truth is when person this close reveals something like this so young you're kinda stuck and having troubles how to feal with it, help her, and make you both comfortable and easier. Please, any help?