How can I propose her when she perhaps has no feelings for me?

Hi friends! I m 26 years old. I just ped my Post graduation (M.C.A). In my college days, I have a junior girl named Meghna Khatri. She is now 20 years of age. She is very beautiful, very talanted & very humble. In my college days I was crazy for another girl who never loved me & that girl was Meghna's clmate. That time I was not interested about Meghna, she casually calls all her seniors including me "Bhaiya" (i.e., Brother) & I also casualy call her "Sister". But I had no brotherly affection about her. Me & Meghna had good friendly relation, we sometimes give friendship sms to each other. Now I ped out. Few days ago I called Meghan casually as I heard dat her mother is ill. She told me that she is looking after her mother now & she will not go outside for post-graduation. Her this responsible attitude ignited immense feelings about her in my heart & I had truely fell in love with her. Now I want to propose her, but I afraid whether she rejects my proposal. I don't want to lose her as she is very good. Now in which way I'll propose her so that she doesn't reject me. Plz help me friends.