My sister in law is two years older than my wife but they could be twins. They look alike and sound alike and wear their hair the same. My wife and I have one son who most weekends are at my sister in laws place since she has a pool. My sister in law Tara was doing laundry at our house for a week since her washer and drier died. She only lives up the block and comes over all the time. It was Saturday morning and I went to the gym. When I came back I saw my wife's car was still in the driveway. I opened the door and called out and no one answered. I went upstairs and checked my son's room and his light was out and the tv was off. I took off my shirt, shorts and underwear and went to my bedroom door which was closed. I opened it and my wife was on all fours playing with herself. I called her name and she stopped and told me she was horny. My dick hardened in seconds and I felt her pussy which was very wet. I ran my penis head on her ass and even went by her asshole. She giggled and said wrong hole. I slid into her pussy and started to slowly fuck her. She was so wet and horny that in a minute she was getting close to her orgasm. I sped up and could her my balls slapping away and I grunted and fired off a few squirts of my cum. I pulled out and laid next to my wife. When I looked at her I then realized it was Tara. She told me she was horny and Fred was gone for the weekend. I smelled your bed and wanted to fuck myself on it. She then looked down and asked me to suck her and my cum off my dick. She did and I went hard again. She sucked me off and after I squirted she told me this was our little secret. I told Tara okay and when she left I got up and went to the book and opened it and hit the stop button. I downloaded the video to the computer and went and took a long needed shower.