Subconsciously you have always at least been Bisexual, But this recent events and in particular witnessing your Daughters blossoming sexuality has sparked that subconscious desire into the forefront of your mind, I have been Bisexual all of my life and I have met other women who like you had always considered themselves "straight" one was even a close personal freind of mine and after having sex with me she said she wished she had acted on her feelings earlier as she had missed out in so much and now she has as many female lovers as male lovers,It's good that you are easy going about your Daughters masturbating so msny girls get screwed up by their parents being uptight about such things,I hope that you find a Woman like me who is willing to let you at least try having sex with her to confirm what you already know.