A day in the life of Mia

My sister

Okay so some back ground info my sister is emotionally and mentally unstable. A couple years ago she terrorized our family we had to call the cops on several occasions. It's a lot less now but when we were younger it was worse. Every time someone tried to touch me, hug me, give me a high five I would flinch away.
My sister has put me in a state of constant fear even when she wasn't around. She's better now but it still happens from time to time. It's 5:13 am and she's refusing to take her meds we're at the beach and we're making the 13 hour long drive home.
The night before my parents and my sister got into a huge fight. The condo we were at staying in got trashed. She ended up banging on my door and trying to get in I was scared for me life. My parents think I'm being over dramatic but she used to physically and verbally abuse me, we used to be super close and she says she's trying to get better so we can be close but what she doesn't understand is that for me our relationship is unfixable.
She's unbearable she's so rude to our parents. She has no filter she'll just shout rude and obnoxious things at any time. I don't wanna complain to my parents cause it'll sound like I'm victimizing myself. What should I do? Lol if any one is even reading this comment some advice.