Prude step-Mother-in-law Fucks Her step-son-in-law

I'm a prude ********* teacher at home, grading papers. Suddenly I feel extremely aroused. I don't understand it, I never do things like this. I haven't been sexual in any way in many years, not since long before my divorce. I try to ignore the feeling and go back to grading papers. Suddenly I have an overwhelming urge to masturbate. I'm ashamed of the feeling because to me, masturbation is wrong and filthy. But the urge is much too powerful and something comes over me as I begin to indulge myself in self-pleasure. I'm so wet that it just turns me on even more. As I'm about to cum I hear my step-forbidden-in-law pull into the driveway. I was expecting his arrival but not this early. It's too late to stop since I'm so very close to cumming but I know once he walks around the corner he will see me there with my legs open and exposed. As he is there staring at me, I orgasm right in front of him. The words asking him to "leave" just aren't coming out of my mouth. Instead I tell him that "I'm sorry, I can't stop". I'm so humiliated I just want to run out of the room crying. I try to leave but instead find myself pulling him in closer, seeing how hard this made him. I can't fight the feeling and I tell him "the only way to stop is for me to get fucked", shocked by my actions and words coming out of my mouth. My body just isn't listening to me and find myself slowly letting the tip of his cock fuck me until I fully give in and ride his cock like crazy. It's as if years of sexual aggression was all coming out at once and taking over my body. Finally, I succumb completely to my primal urges, and decide to just embrace and enjoy it. I beg for him to get me pregnant over and over. Soon as I orgasm he gives me the BIGGEST cream pie ever. His load deep inside of me feels endless. I soon realize the full meaning of what had just happened. I fucked my step-forbidden's husband, and with that much cum, I'm guaranteed to get pregnant. I rush to the bathroom to try and wash it all out of me but soon realize the mistake I have just made and am left there feeling like a dirty filthy slut.