Forbidden visual

So this happened a couple years ago, but it lead to some of the best jerk off sessions I've ever had.

I was walking around my house and the only one's home were me, my 16 year old sister and my mother.  It was about 7 at night and my mom was cooking dinner and my sister had fallen asleep. As I walked by the living room where she was sleeping, I looked at her and her shorts had shifted to the side. There was my 16 year old year sister's pussy , fully on display for my viewing pleasure. I saw that she had some hair , but had been trimming it. It was matted down from some sweat, but you could see the hairs . Her inner lips protruded a little bit, but only like a little ridge line. The second I saw her, I become instantly hard. 

My mother was literally 1 foot away from me, but I couldn't stop staring. I burned the image into my brain, then quickly went back to my room. I shut the door quickly and pulled out my rock hard cock. It only took a few strokes to cum, but I came like a fire hydrant. I couldn't stop thinking about her pussy, no matter how wrong it was. I jerked off at least two more times that night to that image, and I still to this day cum sometimes to it. Oh it is so wrong, but it is one of the best things to make me cum.