My twin sister and I became closer than ever (PART 17)

I'm M20 and she's F20, reminder: Her "girl" came over and they got inside my sister's room without locking the door.

The blonde's name is Lisa. The door wasn't locked so I carefully opened it but just enough so that I can see. Both my sister and Lisa were simply sitting on the bed, chatting. I noticed a few sextoys on the bed near them, probably my sister just showing her collection. (If I didn't mention it earlier, my sister has a massive collection of sextoys she hides in her closet. She makes money using them and recording herself then selling the tapes + sextapes with girls. It's her business and I support her for it, altho recently she has stopped for a while.)

I came back to my room and waited 2 hours. Then I went back, the door was still unlocked and I was finally hearing moaning noises. I opened slightly and I saw them fully naked, Lisa eating out my sister's pussy in between those fat thighs of hers. That got me hard that I had to take off my pants and started masturbating on her door. It felt sooo good, it wasn't like watching corn at all ... this was a masterpiece of reality. For the first time, I was looking at my sister having sex and the way she moaned while she held her sweaty bouncy tits made me cum on her door. I wasn't seeing my twin anymore, but my soulmate, I was now romantically interested into her.

Obvs, my sister saw me banging my dick on her door. She waved at me to come in. I made sure her big ass camera wasn't recording from the side, I didn't want to be in a sextape. So I went in. Lisa's big asshole was right in front of me as Lisa was eating out my sister. I dropped my pants down, my sister yelled at me while whispering "FUUCK HEEEER THIS IS YOUR CHANCE"

I really hesitated. Lisa was still a stranger to me, my sister said the same thing again and Lisa looked up. She noticed I was there and screamed covering herself with her hands as my hard wet cock was standing menacingly.

Lisa: "YOU GUYS ARE INTO INCEST SHIT WTF"

Part 18 later