My sister embarrassed me in front of my close friend?

Okay basically I went to see The Conjuring and my sister tells me to come from at 9;00 so we can make our way to the movies.

I come home 8:56, she yells at me that I didn't bring my phone, how we are gonna be late. So, I open the house gate and the key is stuck. She gets out her car, fuming and then snatches the key out of the lock, with my friend watching in the car. And then we watch the movie and we come out and there's four of us. Me, my friend (let's call her Jada) and my sister and her friend (let's call her Tina) so me, Jada, Tina & my sister are walking back to the car and then my sister says wow that film is scary and I said yeah and she was like I wasn't talking to you.

Why is she so mean to me? I'm sick of it :( she's so horrible