My ex wife had 3 kids with her first husband. She had 2 girls, and a boy being the youngest. Her second youngest daughter was not very attractive, and overweight. We were very close, and had very few friends so she would confide in me often. One day she told me that guys didn't even look at her, and she would never have a boyfriend. We discussed this for some time, and you could imagine my surprise when she asked me if I would be her first. I initially said no, but after much discussion she convinced me it would be our secret, and it would never happen again. I reluctantly agreed, and we began making plans.
I decided the house or a hotel was to risky so we came up with the idea to use a storm drain tunnel near the house. When the day finally came we brought an old beach towel, a flashlight, and a condom with us. When we we got far enough inside the tunnel we turned on the flashlight, and walked until we were far enough in we felt safe.
I told her she should be on top so she was in control, and she agreed. She was embarrassed about me seeing her body, so I told her to just take her bottoms off. Before she took off her bottoms she asked me to turn off the flashlight so I did. Once it was pitch black we both removed our bottoms, and fumbled around in the dark getting into position.
When I put on the condom, she slowly lowered herself down on me until I felt her hymen tear, and she let out a yelp in surprise. We waited until she felt ready, and she slowly stared lowering herself down on me until I was seated inside her completely. She told me it felt like I was in her stomach, as she rode me.
She was so tight compared to my wife I knew I wouldn't last long. I was just about to cum when I suddenly felt the condom break. By then it was to late! As soon as I started ejaculating inside her, she orgasmed almost immediately. She had no idea what was happening, and it seemed the more I tried to stop, the harder I came. At this point it didn't even matter to me she could very well get pregnant as she wasn't on any form of birth control.
Before I even turned on the flashlight I could feel the mess all over my crotch. When I finally did turn on the flashlight, my stepdaughter slowly lifted herself off me. When she looked down, and saw all the blood, and semen leaking out of her all over my crotch she panicked. We quickly got on our feet, and I handed her the towel. As she cleaned herself up, she was in tears about her chances of getting pregnant. As the adult I tried to give her reassurances she would likely not be pregnant but deep down I was as panicked as she was.
When we finished cleaning up, and getting dressed, we left the blood soaked towel, and condom there, and headed back home. She was really scared she would get pregnant, but I assured her I would pay for an abortion if she was. Luckily for us her period came a few days late but it came. We never did it again, and we haven't spoke of it ever since.