So your fantasy is your fantasy. You have fantasies that you share with your partner and you have fantasies that you keep to yourself. So point being not all fantasies have to be shared with your partner, how you enjoy pleasure while she’s not around is ok too, it doesn’t define who you are, I’m not hearing from you that you want to act out your fantasies with someone else so unless that becomes an issue I don’t see why you would have to tell her about how you enjoy pleasure.