Mixed Feelings

So. I'm in a great relationship with this guy, and we've been together for almost 7 months. He's the most amazing thing ever and I love him with all my heart. But I'm bisexual..and there's this girl I really like. We're best friends, and she and I have been close for almost 2 years. She sorta likes me back, but I'm not sure. I kinda like her too. I previously had a crush on her a long time ago, before she came out as bi, but when she did I definitely chickened out because she's this really pretty blonde with blue eyes and she's so confident and everything. I just couldn't see myself being anywhere close to a great girl like her. And when she told me she liked me back a month ago...I just didn't know what to do.. she's amazing, my best friend. But I also have a loving boyfriend that I wouldn't trade anything for...help..?