Summer with the family

>Be me , about 10, have 12yo cousin staying over for the whole summer
>Hated the bitch, always picked on me
>One day, be playing OoC, leave for 5 mins to take piss.
>come back, find her with the controller behind her back, and her watching some bullshit on the tv
>Get mad like the dude from Network
>She laughs at me
>That's it. Gather all my might and try to push her off the seat
>Struggle to get her off, end up with her on the floor and my hand cupping one of her buttocks completely
>I'm scared to death, sure she´ll scream and tell on me
>She only giggles and says "Hey, watch your hands, anon"
>take my hand off like I had put it in hot iron
>she giggles at this some more
>says "you ever play "show me yours, I'll show you mine"?"
>say no ,with a mixture of fear and pure arousal
>she unties something in front of her pants, and seats down again, spreads legs and puts feet in the arm rests
>My penis is so hard it hurts
>Her panties press against her pussy, white with red edges with balloons on them.