sex with my cousin_(1)

For the past year my cousin Mary has been living at our house; as her parents had moved to Ireland, but had to leave her with us in the US because of having trouble getting her a visa. However I didn’t mind, as being only having a older brother, who was 16, I did not have anyone of my own age that I could interact with, so I got quite lonely at times. But before I continue let me introduce myself, my name is Tim and I’m 13 years old. My cousin Mary is also 13 years old and has long brown hair that goes down past her shoulders, hazel eyes and some very nice if a bit small breasts.
It was a Monday evening when I was in my room playing my Xbox, when I heard a creaking coming from my parents room; which I found weird as my parents had gone out for a romantic meal together and had left my brother in charge, as they thought that they might get a hotel for the night. So with this anoying creaking noise putting me off my game, I decided to go and find out what it was. I opened my door and poked my head out into the corridor and saw Mary on her knees and looking through the rather large key hole in my parents closed door.
I decided to walk over to Mary and ask her what she was looking at. As I tapped her on the shoulder to get her attention, she jumped back and just about muffled a shriek. I apologised and asked what she was doing, she just put a finger to my lips and with her other hand, pointed to the key hole.