After Being in a Relationship for Half a Year, My Best Friend's Brother Said I Was Just a Sister

I'm in love with my best friend's brother. After dating for half a year, she still knew nothing about it, so she took me on a single date at Christmas. Unexpectedly, she unexpectedly saw her brother Lu Chi interlocking with a girl and kissing under the fireworks. "Damn, my brother finally caught up with his goddess." My best friend looked excited and pulled me forward to say hello. Lu Chi touched his nose awkwardly and introduced to his girlfriend: "This is my sister, and next to her is her friend... Who is also half my sister." I laughed silently. After kissing her on the mouth, she came back as a younger sister. Introduction 2 Spending Christmas with my besties. Occasionally, she met her brother Lu Chi and his girlfriend, holding hands tightly and kissing under the fireworks. "My brother finally caught up with the goddess, let this kid do it." She excitedly pulled me forward to greet them. Lu Chi touched his nose awkwardly and introduced to his girlfriend: "This is my sister, and next to her is her friend... Who is also half my sister." Sister? I smiled bitterly. That's right, I'm just his sister who he's been secretly dating for half a year.