I am a 16 year old girl. My parents are divorced. Officially I live with my mum together with my 14 year old sister. But she is an alcoholic now and often in a bad mood. I also hate being confronted with the nasty men she takes home. Hate running into them in the morning to see them looking at me as if they want to fuck me too. So since a year I mostly stay with my dad and stepmom and take sis with me.
My stepmom is absolutely stunning. Very classy and sexy at the same time and apparently very successful at work. I can totally see why dad loves her. In the beginning when I stayed with them she was very decent, always making sure not to walk in on me in bedroom or bathroom and always making sure she was dressed properly.
Last summer I held my birthday party at their home with a bunch of my girlfriends. They had promised to leave us alone and go out. After my friends had arrived she came down ready to go out. She was looking incredibly beautiful, wearing a short white leather dress that was clearly very expensive and overknee socks and gorgeous black shiny high heels. Her fit body was perfectly accentuated. My friends were in awe and talked about her for at least an hour after they left. The conversation about her was quite suggestive and they wanted to know what she looked like naked.
The party was wonderful and by midnight everyone was getting ready to close the evening when dad and stepmom also came home. She came to talk to us girls and was pretty drunk but in a very fun way - not the nasty way of my mum. She lowered herself between us on the pillows that we had put on the floor to sit on and started engaging discussions with my friends. They loved her clearly. I sat opposite of her watching them talk. I was admiring her beauty, eyeing up her body. Then suddenly moved a little to get more comfortable. I suddenly got a quick peek under her dress and where I expected to see panties I saw nothing... She was not wearing underwear. I saw her shaven pussy. She must have noticed my shocked look and gave me a smile. Dad had already gone to bed so when all girls had left she helped clean the mess. Halfway through This job, she stopped me, took my hands and apologised if she had upset me. She explained that me being 16 now made her decide to be more herself again because I should be able to deal with it. And yes indeed, she never wears underwear and only did it when I was around. And that she hoped that I am not shocked as some of her friends were not when they saw and they actually discussed it. I said it was ok, I needed to work through this in my mind and maybe we'll talk about it later. She gave me a hug, told me that she was very happy to have me in her life and abruptly said that I needed to finish up as she needed to go to bed as otherwise dad would be asleep already. We kissed, she went upstairs and I finished. When going up myself I heard her voice in their bedroom telling him to shape up. Telling him she needed it now. I held my breath and quietly sneaked into bathroom next to their bedroom and started undressing. I heard her now saying that she needed to get fucked. My dad told her to be quiet as I might be able to hear as he heard me going into bathroom. She laughed and challenged him. "Do you still see her as your little innocent girl"? Laughed again. She teased him by saying that I am a big girl with my own insatiable sexual needs. He protested. She pushed on by telling him to grow up and see that his girl has turned into a horny teen girl. That I have probably inherited the slut genes from her my mom. Then I was shocked to hear her say that she knew I had been borrowing her vibrators. He told her to be quiet, that I might hear her. This only made her talk louder. I guess the combination of alcohol, being horny and having to behave for a long time made her go all out. She told him that I had seen that she was not wearing underwear, which clearly shocked dad. Then she started playing with my poor dad by making stuff up. She said that she and I just had a conversations about it and that she had explained to me that she loves flashing her pussy and the attention and that she loves being my dads slut. And added that I loved it and asked her to teach me. So you see she said, your girl is a little slut like her mum and me. Now fuck me. He told her to be quiet again. She started telling him to fuck her louder and louder now, threatening him to started shouting if he was not going to fuck her. I am your dirty little slut who needs your gorgeous hard cock now so fuck me. Fuck me like the slut you want me to be, come fuck me now. Apparently he gave in as I heard movement and a load yes from her and then I heard them fuck. She was pretty loud now, telling him how much she needs to feel his cock. I was so turned on by her that I started to masturbate frantically. When I heard her come the first time I came too. And pretty loud. They continued to fuck so I decided to try to see if I could peek in. Yes she had left the door slightly open so in the dark of the hallway I peeked in to see my dad taking her from behind and masturbated again and again came when I heard and saw her come. She so so turned me on. It's was not my dad's cock or something that turned me on but her totally loving to be fucked. She turned on her back facing the door and told him to cum inside her, make her feel his cum in her pussy. For s moment I had s clear view of my dad's impressive hard cock. When he pushed inside her she looked in my direction and smiled. I am sure she could not see me in the dark but maybe I was wrong? Quickly went to my bedroom next to theirs, took the vibrator I borrowed and pushed it inside me while all naked on top of my bed. I came again when I heard her come but could not stop, continued to fuck myself. I heard her walk into bathroom, Pictured her naked, closer my eyes and came again. When i openend my eyes she stood in my doorway, naked, watching me and smiling. I was so embarrassed but could not move as it was too horny to have her watch my naked body and show myself to feel slutty too. All she said was that this thing made quite a lot of noise so she had to come see and said she loved it. But maybe we should go buy me a more quiet one as even my dad had clearly heard the vibrator. I was totally embarrassed but even more turned on now. She walked over, kissed me and said sleep well.
The thought of the vibrator being heard turned me on so much. The idea that both my dad and step mom were in bed maybe listening to me fucking myself made me so horny that I did it two more times, making sure that they could also hear me come.

More happened in the months that followed, another time