This is a secret life...  you take the details with you to the grave.  You don't tell your brother, your best friend, your buddy and certanly not a GF.  
"You had Girl Friends before".  "You thought they were attractive" (though saying so to a new GF is dangerous) perhaps "you thought so at the time".  How long they were your Girl Friends for is between you & your conscience.  
Keep your hobby life separate.  Separate hobby phone, separate secure email, do not leave tracks like use of Credit Cards or EZ Pass somewhere you should not be.  At any time you can shut the Hobby off by closing the door.  

Best wishes,
skb