I’ve known my wife for over 11 years and we will have been married for 9 years in September. She has an adopted sister who is 10 years younger than her. So when I met her she was about 11 years old. Since then, she had developed into a big titties, no bra wearing lesbian and as wrong as I feel about it I want to fuck her so badly. She came out last year and in an effort to connect my wife revealed she was bi and that we had group sex occasionally and since then her sister has become a lot more comfortable around us. Telling us about her sexuality and more and more about her experiences. Sense I’ve found out I can’t help but fantasize about having both her and my wife. I justify it by saying she’s adopted. I’ve come up with scenarios where I volunteer to donate sperm to her when she wants kids but it’s in a threesome form where I get her and my wife pregnant at the same time. Over the last year since she’s gone off to college we have gotten a lot closer to the point now that she says stuff to make me feel uncomfortable about how she likes sucking cock or being bent over. She will often start singing really explicit lyrics in front of me just to make blush. Lately my dick had been rock hard. Now she’s staying with us for a week wearing short shorts and no bras and walking around with bare feet and I can’t help but stare. The other day while my wife was out with her running errands I sniffed her panties and they were so rank I could imagine she was soaked all day too.