Hi, could someone tell me if this is written correctly, please? and if the idea is clear??

This happened to me 6 years ago, when I was studying at the university. I and my cousin were at our little room telling scary stories, it was very late at night. My causin scares very easily and she always yells and cries when she is frighten. We were at the table I was sitting looking at the window and she was with her back against it so she couldn´t see if someone was behind her.
We were so concentrated in the stories we were telling that we didn´t realize that one of our friends was outside looking at us through the window. Then, when I turned my head to look outside I suddenly saw her grabbing from the protections of the window and looking at us carefully. I got scared and scream from the sudden vision; but my cousin got terribly frighten because of my scream that she yelled very loudly jumping from the chair like a crazy person and since we were both yelling and afraid, my friend got scared too and tried to run but she didn´t know where to run because she was outside, so while trying to do so she made like a little dance and it was so funny, then we all were laughing because we had scared ourselves.