the best that you can do right now is wait. you don't want to tell her that you love her when she is dating your best friend because it'll make her feel awkward and will probably make your best friend hate you. if they eventually break up, wait about a month for her wounds from her broken relationship to heal and then gently ease into revealing to her how you feel about her. as long as you're gentle and open, and not blunt and expect instant results, she'll appreciate that you can be so honest and open and she might return those sentiments. if not its ok there are plenty of other chiquitas out there waiting for a big heaping slice of YOU!!!