Shocked: I watched my father fuck my step cousin SeXStoRY

It was a full house that weekend. My aunt and her step son had stopped over on their way down from Northern Virginia to join her husband who was now living in Southern Florida. No one in the f****y exactly loved my negative and bitchy aunt. I had only met her step son Matt a couple of years ago and we didn't really hit it off. Now, two years later, he was 18, fully developed and even more cocky so we had less in common now than we had then. I couldn't stand that this arrogant prick was having to stay in my room for a couple days. Always a light sl**per, I noticed Matt get out of the lower bunk bed to what I guessed was the bathroom. He was gone for an awful long time and when he came back, I glanced down to notice that he was naked. I hated him too much to be turned on and drifted back off to sl**p but awhile later, I was stirred again. I opened my eye to see my dad tip toeing into my room. The moonlight shone through the window and he was naked. For a minute I thought I was dreaming but no, it was real. I pretended to be asl**p but was dumbstruck about what was going on. Was dad sl**pwalking? No, he was trying hard to be discreet and then, I saw him stoop down to the lower bunk bed where Matt was sl**ping. I couldn't see what happened but assume dad woke him without speaking. Dad was in my room for a second and then quietly left: I watched his handsome and firm backside exit out my door. A few seconds later, I heard Matt get up and he also tip-toed out - naked. What the fuck was going on? I let a few minutes pass and then I got up and crept out. I passed by my s****rs' rooms and my parent's room which I peered inside. I saw mom sound asl**p but no dad. Hmm. The bathroom door was open and dark so no one was inside. Down the steps I crept into the dark ground level. I didn't see anyone in the living room, dining room, kitchen. As for the guest room, all I heard was my aunt snoring loudly so they definitely weren't in there. That left the basement... The door to the basement steps wasn't completely shut and I opened the door to see that there was a light on downstairs. I carefully stepped down a few stairs to where I could get a discreet look at the basement below. the light was on and the whole basement was illuminated. Then, I saw what broke my heart... my father was naked, fully erect and slapping Matt's face with his huge penis. "Yeah boy, you want my cock?" Dad taunted him. Matt acting like a submissive little whore moaned as Dad slapped his cock against his face and teased his wide open mouth. I wanted to run down there and punch them both but I was paralyzed with feelings of anger, jealousy and desire. I wanted to be Matt. Dad teased him for awhile and then shoved his dick into Matt's mouth. I heard Matt choke as dad f***ed his dick into his throat and started to face fuck him. Matt was gagging but seemed to be enjoying it as he was definitely hard and stroking himself while blowing my father. "I'm going to fuck you," Dad told him. "No," Matt said. "I've never been fucked before, let me suck you some more." Dad stood up and flung Matt around. Matt kept saying no but dad kept saying yes and pushing him to his knees. I didn't know what to think. Here my father was, getting ready to fuck another guy - my step cousin - a guy close to my age - who I hated. Matt finally gave in and seemed to relax knowing the inevitable was about to happen. That's when my father smiled and put his face into Matt's ass. Dad kissed his butt cheeks and gently bit on them which Matt seemed to enjoy. He then moved inbetween his buttocks and looked like he was licking his asshole. Matt was now really enjoying it and began to push back on his ass, forcing dad's tongue into the most taboo part of his body. I heard dad spitting onto Matt's ass knew what was coming next. Matt did too as he looked over his shoulder and said "fuck me but gently." Dad stood to his knees and slapped Matt's ass hard. He then got closer and began to rub his big penis into the wet space between Matt's buttocks. Matt's face and grunts started with pleasure and gasped with shock. As dad began to penetrate him, Matt opened his eyes and mouth wide wide like he was going to scream. Dad immediately reached around and put his big hands over Matt's mouth as he f***ed himself inside his asshole. I was so dumbstruck I didn't know what to do but I knew by my own rock hard dick inside my pajamas that I was turned on at the immoral sight in front of me. Dad was fucking Matt hard doggy style and Matt was caught in the gray matter between pleasure and pain. I started to masturbate watching the infuriating site below. Dad, while fucking Matt doggy style, spun his body around and threw Matt's legs over his shoulders. He stood up, picking up Matt with him and really began to pound Matt hard. Matt became totally submissive. I could tell he was in pain but he was being completely submissive to my dad and looked like he was starting to push his butt down more on dad's cock to take it deeper. Matt whimpered "fuck me" over and over but he was not in control. Dad held him in the air and pumped him relentlessly. I guess dad's back got tired because he then set Matt down on the floor but f***ed his legs wide in the air and open. Matt was on his shoulders and upper back in what looked to be an uncomfortable position. If it was, he didn't have a chance to say anything because Dad got up and stood over him, back to his face and started to fuck him backwards, dipping his cock furiously in and out of Matt's wide open and now red hole. Matt now began to moan loudly as dad plunged deep inside and out of him. I myself was getting excited but didn't want to them to hear me so I stopped masturbating. I watched dad's face get tight as he started to dip deep and then he said rather loudly, "I'm going to cum!" Dad kept pumping and began to shake and moan as he shot his seed into Matt's spread eagle asshole. Matt was definitely feeling his warm semen because his faces of pain turned to faces of pleasure as dad began to ejaculate. Neither of them saw me as I creamed into my pajamas while dad was creaming Matt. Matt was totally focused on his ass so he was soft but was in heaven. After I had managed to cum without making a noise, I knew I had to get out of there before they saw me. I crept up the steps, the last sound I heard before exiting was dad's hand slapping Matt's cum-filled ass. Upstairs I crept back into bed and acted asl**p. About five minutes later I heard Matt tip-toeing back inside. Watching him in the moonlight, he now walked with a limp. My dad had fucked him good and hard. The next day I woke and didn't even say good morning to Matt who laid there with a big smile on his face. CHECK OUT MY PROFILE FOR OTHER STORIES IN THIS SERIES: 1. Worshipping my father's feet while he slept 2. Dropping my son off at school then… 3. Getting a physical exam with my father 4. Secretly watching my father masturbate 5. Blow job while my wife slept beside me