I agree with giga ,its too complex,I mean if u were actually in a relationship with her it would be different,but shes just ur friend,and although being with ur best friend is pretty awesome,its not worth risking it if shes already seeing some other guy?maybe when she said she didnt have feelings for him,she just wanted to get u off her back?ur right on that one.just leave the whole thing,its too tangled up.
"Nobody , so long as he moves about among the chaotic currents of life , is without trouble. Carl jung