Is it normal to watch porn with my younger sister when parents are out?

I'm 20 years old and go to college in anther state but home for the summer. My sister is 14 and just finished her freshman year of high school. I am the older brother. When I came back home, I hadn't seen her in a few months and was pleasantly surprised by how much more...physically developed she looked compared to when I last remember seeing her.

Needless to say, even though we didn't have the best relationship before, I started being nicer to her and helping with her chores and telling her stories about college and people I met there and just looking for excuses to hang out with her around the house.

Last week one night it was a real crazy thunderstorm and I was downstairs playing some video games in the living room. My sister came down to drink some water but then she told me she was scared and wanted to watch me playing video games for a while. So I let her sit down the couch next to me. Before I know it, she's holding my hand and sitting in my lap. All of a sudden I remembered how she used to hold my hand when we were both a lot younger whenever she was scared of something.

And I just thought how funny it was that she now had the body of a full grown woman but was still acting like a kid, all cute. She then said that she missed me when I was away at college and she wanted me to give her a hug. Then she did the weirdest thing. She turned around on my lap with her crotch right on top of mine, put her legs on my side, put her arms around my neck, and put her boobs in my face. She told me grab her ass and bring her in closer to my body.

At this point I was grossed out. But then she blackmails me, saying she would tell mom that I was touching her....unless I watched porn with her. So last Saturday when our parents left for a few hours, I had to watch porn with her. She even told me to masturbate in front of her and I was nervous because my sister had never seen my penis before so I literally told her that I was not going to listen to her anymore and that I was recording our whole conversation on my phone (I wasn't).

She just turned off the porno ands told me that she would turn my life into a nightmare. Now I'm scared as hell and don't know what she means. My little sister is abusing me and I'm scared for my life.