Crush on didi’s friend

I (18 M ) think i like my sister’s friend. Recently, me and my sister (19 F: uncle ko xori) were traveling on bus, and i got to know that her friend was also coming. I had heard her name earlier but hadn’t seen irl. Me and my sister were on a same seat and her friend was sitting next to us. They both were gossiping about their things ,but I hadn’t spoken a single word as it was the first time that we met and i also felt awkward. I was looking to her the entire time—she’s so beautiful. I also searched her profile( still continuing to stalk). I haven’t tell anyone about this topic (not even my sister). I’m thinking to tell my sis, but I’m scared about her reaction. What should i do? Idk if it is a good choice to tell her or not. Helpp