Where is this friendship going? I mean.... Im not a lesbian or bi and neither is she?

I have always been a hetero-sexual woman. SO has she apparantly. Im 33 and she's 39. But so far we have kissed, touched, 'had sex' ( as in fingering), and she says she wants me to b her girlfriend...and I am falling for her. Onely 2 problems. She does not want her mom to know and I dont want my family to know and she lives about 40 miles from me.