Falling in a forbidden love

My names Lexi and I have a best friend called Lucy. We've been inseparable since we started secondary school. We share secrets, clothes, gossip, everything. But there's one thing I haven't shared with her. I have the biggest crush on her older sister Jasmine. I never really noticed her until until she hit puberty and I realised I liked girls, but that was two years ago. Every time I see her my stomach gets butterflies and I can never control myself in front of her. She just sees me as her younger sisters best friend. But since I hit puberty, and believe me it hit me hard thankfully, I feel her watching me more. I'm sure its just my wishful thinking but what if its not? What if since I've grown a pair of boobs and an ass she sees me as more? I couldn't do that to Lucy, she would be so hurt to know that I betrayed her like that. But now I don't know what to