My sister’s boyfriend came with my cock inside her ass

The day that my sister's attractive boyfriend told me that she was bisexual, it was a special day for me, since just then i knew that at some point we would end up fucking. he is a handsome, athletic and stringy boy. i honestly think it's too much for my sister, that's why i felt compelled to have sex with him. on that occasion he and i were alone, the boy arrived at our house a little before my sister arrived, so he sat next to me to wait for her. just then our eyes met and we both knew we wanted each other. without saying anything to each other, we kissed each other and began to undress until our naked bodies rubbed each other. then i ate his cock while he looked to see if my sister could arrive at those moments, luckily it did not come. it was then when he sat on top of my cock and, while i grabbed him by the neck, i penetrated him hard, so we were fucking for a long time until we changed positions to see our faces. at that moment my supposed "brother-in-law" couldn't take it anymore and he ran on his own chest, surely with my sister he didn't come so soon. seeing him, i got excited and ended up cumming on him too. this will be our great secret.