I try not to look obvious as I wait for Mom’s answer. I feel as if I am on the edge of a knife, my feet being sliced by the blade, teetering toward one side or the other.“Oh, of course!” Mom exclaims, her voice trilling with laughter. “How could I have forgotten?”And now I know. Really know. This woman is not my mother. I don’t know who she is, but I know absolutely who she is not.