I think that your wife, although confused, is acting in an extremely selfish manner, and not thinking at all about your feelings.  The same thing happened to me with my husband, who expected me to empathize with his situation and to comfort him in his trepidation about his future.  At the time, I saw his need as a good thing ("He still needs me!  He still wants me!  If he's asking for my help it means we have a future!).  I no longer do.  Now I think they're selfish.  And because they are, we have to harden up our hearts and become very self protective, because they are thinking only about themselves.  Why should you allow yourself to become merely of use to her in an experiment of "am I lesbian or am I straight?"  Let her move out, and figure it out on her own, and if she decides she wants to be married to a straight man, come back.  My two cents.