I discovered my stepsister having sex with her boyfriend and threatened to tell our mom unless she had sex with me

I stumbled upon my stepsister getting intimate with her boyfriend in the guest room. I had to think fast. I threatened her, saying I'd reveal our secret to our mom if she didn't fulfill my desires. I demanded she satisfy my lustful needs. She hesitated at first, but soon gave in, revealing her luscious curves. Her ample bosom and voluptuous derriere were too tempting to resist. I took control, showcasing my impressive endowment. She moaned in pleasure as I delved into her depths. The sight of her writhing in ecstasy was enough to fuel my own desires. As we reached our climax, I couldn't help but compare it to popping a balloon, so intense and satisfying. This was a turning point in our relationship, a secret we now share, adding an extra layer of excitement to our already tumultuous dynamic.