Helplessly inlove with my best friend

We grew up in the same neighborhood, his parents are billionaires, while my parents worked for his parents, but they were too nice, to sponsor my education. I went to the same school he attended, he protected me from being bullied, while I help him with his assignments and to keep up his grade. He is a great dancer, and I dance very well too, we usually practice together, we read together, and he tells me everything about himself while I tell him almost everything about myself too. He was everything to me, he was that brother I never had, and I was the sister he never had, people see us more like siblings than just friends, because of our closeness, and because of his status and protectiveness, I also became popular. I watch him date hot beautiful girls, he asks me for advise him, on how best to treat them and I tell him, but I was dying inside, he even encouraged me to date one of his friends, and I did, just because he said it, but I could never love his friend, the way I love him. I really want to leave the friend's zone, but I am scared, telling him how I feel, might put a strain, on our friendship, and that is worse, than death itself, but how long can I keep hiding my feelings for him, I really need to leave the friend's zone.