girlfriends young cousin

one time this girlfriend i was living with for a while used to have her young female cousin stay over. she was about 11 or 12 .they used to sleep in the same bed and i would sleep on the couch in the living room when the cousin was there. i just thought well it's like a sleep over. one time they slept on the floor in the living room .I had came out to get a drink i must have surprised them as i saw the young girl pulling her hands back from under the blankets and my girlfriend looked like she was kind of in shock so i just went back to bed. .this young girl would stay over many times and i was wondering if something was going on. then one time they went to bed and i could hear noises so i went upstairs, the door wasn't completely shut and they had the lights on on the nightstand . i could see the young cousin fingering my girlfriend and my girlfriend feeling the young girls little tits. i nearly came at the sight even though i know it was wrong. i kept watching and as they got more into it they were fingering each other until they

My girlfriend Clair and I moved in together last year when we were both 20. Sometimes her younger stepsister Jen who is 13 comes to stay for the weekend and when she does, I sleep on the sofa in the living room and let Jen share the bed with Clair. They are always hugging and stuff but I never thought much of it. Jen is a cute kid and already has decent size tits for a 13 year old.
When we would go to sleep, I hear them laughing and joking but sometimes I hear other things going on. They whisper loudly and make weird noises. I always wonder what is happening. This goes on every time she comes to visit.
The other day I came back from work early and when I went upstairs I could hear water running so I knew someone was in the shower. I called out but nobody heard me. Then I heard sounds coming from the bathroom and Clair was saying stuff like… yeh yeh do it faster.. more… more and her stepsister was saying… does that feel good. Then I heard Clair saying… I”m coming don't stop. Then she screamed out… wow that was amazing. Now your turn. After a few minutes I could hear Jen moaning louder and louder until she shrieked yes yes yes yes. Then it all went quiet. Clair said… do you feel better now and Jen said OH YES. Clair said Do you want to do it again. and Jen said YEH so Clair said then lets do it together. I knew they were masurbating each other and over the next ten minutes I just listened as they were moaning and crying out. Jen asked her if they could rub their titties together and Clair was like… YEH. Then Jen says… push two fingers in me please and squealed as Clair must’ve done it. Then Clair says I’m coming I”m coming do it more and faster.
I’m sitting on the stairs hearing all this and by now have a raging hard on. I got my cock out and started to jerk off. Hearing Clair coming was taking me over the edge and when Jen started to come again and was screaming at Clair saying Don't stop now…. that was it. I Shot my load into my other hand. Now I’ve got come all over my hand so I ran into the kitchen with my cock hanging out and washed it off real quick. I zipped up and went outside like I was never there. I walked around the block for about 20 minutes and then went back home. I opened the door and yelled really loud… Hi I’m back. They were both in the kitchen and dressed by now. I asked… so what have you guys been up to today. Clair replied… not much just doing girlie stuff..
If only they knew that I knew……