Few years ago , (M)18 lived with my girlfriend at the time (F)18 and her family. It was her old brother (27) male and his baby mama (25) female , and my ex broke up with me one day said she needs a break . A few days later , her sister law texted me after everyone was sleeping how she wants to give me head and then fuck her on the living room couch where everyone sits . Was rock hard in a seconds and definitely felt so taboo but naughty fucked right there on the couch . We hooked up a few more times in that month . Felt so wrong but amaxing sex . One day after we took the kid to school we came back and usual we played and hooked up and that day she asked me to fuck her raw cause she on birth control . Didn’t take much to convince me . I came so much that morning . (Not know what would happen later )that night my ex came back and told me how she wants to get back together, but then jumped on me telling me how she misses my cock . I caved and fucked her that night . The thrill of having her sister in law that morning was incredible , and knowing that and not my ex i went feral and went fucked her hard . Few weeks after we got back together she asked me if her sister in law ever tried to flirt with me and sleep with me during our “break “ and I said no of course not I’m not attracted to her . Wanted to tell someone couldn’t tell my ex ever .