Hey i am a guy and my best friend who is a girl . weve been friends for 5 years,i think i am in love with her?

the problem is around 3 years earlier she hinted me that she loved me . once i was going to leave the city and she cried badly but then i didnt realise that she loves me and so do i and now when ive realised shes started ignoring me . we have never talked about it openly and now we still talk to each other but i feel as if she is doing it for formality , i am not sure what to do . I am afraid that if i tell her that i love her i may lose her completely .once i proposed her and she gave me a big smile but immediately after that joked about it !