It happen a year ago and guess I just let it happen. I had been friends with this girl for several years and met her on the last two years of college. She was married to this nice guy and never suspected she was bi-sexual. She invited me to her house for drinks and don't know how our conversation drifted into talking about sex. It was hard not getting aroused talking about those things and guess she did it to get me in the mood. I don't know if I was shocked or just tipsy with the drinks, when she leaned over me kissed me and slid her hand under my skirt. I guess her kissing, her finger under my panties sliding over my soaked clit felt so good, I completely melted away with pleasure. The ice had been broken and found myself half naked on a sofa with my girl friend ravishing me sexually, when her husband walked in on us. My first reaction was pulling down my skirt down, hearing her telling me it was alright and all three of us ending up naked in the living room having a sexual threesome. I was then when I realized she had a swinging marriage and her husband meant to join us. I remember his dick hardly fitting in my mouth and my girl friend between my legs giving me oral. I practically got eaten alive, soar as hell the next day, field with guilt but mind blowing orgasms that wouldn't quit and totally sexually satisfied. A peaty because it only happed once and would have gladly done it again.