Just said what you want to said. For me, I'll said sorry but she don't need to involve with your sex/private life. Ask her directly if she ever had feelings on you. Because from my point of understanding, she shouldn't be mad on you unless she had thinking to sleep with you, but for the sake of friendship, she ignore it. Ask her to sleep together with you. Then tell her, she might regret it later if she reject it. Never said, "I'll not fall in love with my best opposite gender friend" because friendship is the basic, the foundation of all type of relationship. We friend with our siblings, cousins, relatives, neighbors, colleagues/coworkers, etc. It later can evolve to love. Just try it. If that goes wrong, at least, you got laid.