My ex girlfriend little sister

Me and my ex girlfriend was arguing so I went in the living room where her little sister was she said it's cold can u come hold me till I fall asleep I said ok so I laid down with her she started moving her hips and my dick got hard and she asked what's that against my butt I said nothing she kept moving her hips she said it's big what's that I said u really want to know she said yes I said ok and put her hand down my pants she touched it and said what's that my pepe she said can you pull it out I said no your sister is in the next room she aww ok she turned around and kept moving her hips I said wake up I pulled my pants down and she said Damm it's so big she grabbed it and started stroking it and then put it in her mouth I said how u know to do that she said watching u and my sister I said oh ok and she kept going faster and faster than she started deep throating it I started feeling on her little pussy I was 18 and she was like 15 so I started feeling on her little pussy she started moaning where her sister came out and said wtf y'all doing she kept sucking my dick I said what it look like getting some head