What am I supposed to do about this?

I'm helpless. My sister, the goody goody "I'm perfect, beautiful, smart, and I know exactly what I'm doing", can no longer keep what she's been doing away from me.

I've always known that she was a bad girl in high school, but I could never back it up because I had never seen it. Not one picture was on facebook of her drinking or, dare I say it, doing drugs; let alone sleeping with people. She'd never come home drunk or high. I was naive, and I knew it.

She recently went to college and I had the feeling that she was going to let her wild self go, now that she didn't have me and my family to watch her. But now it's inevitable, and I'm beside myself.

My dad refuses to even think about the subject. "I have no evidence that she's doing any of that. Don't blame her of something we don't even know about."

I don't know why he's so against having opinions about my own sister. "Dad, you can't deny the glaciers are melting just because you haven't seen it." I've told him, with thousands of other examples that he just laughs off like it's no big deal. I feel like it'll take until she's in the hospital because she passed out drunk.

Dad thinks we're over exaggerating, like it doesn't happen to at least 20,000 people every year between the ages of 15 and 30. Fact.

I want to confront her but she'll just get really mad and not talk to me.

Katie's never gotten busted for anything and my parents have been living in a dream world this whole time. My mom more in touch with reality then my dad, still holds onto her faith in the little Katie she used to know.

I've never looked up to Katie, even when I was little. She always treated me like I had two barely functioning brain cells that did nothing but allow me to eat and breathe. Mom said she'd change when she went to college but she hasn't at all, and instead of bring us together it's brought us further apart. We can't talk anymore. She doesn't value my opinions at all.

I can't do anything because she's never listened to me even before this whole thing. If I brought it up, mom would stick up for her, dad and Madie too, even though they've been on my side in the first place.

Everyone's afraid of Katie but me. I swear to god, I'm the only one that's ever told her how I really feel about how she acts. They think I'm just being hard on her, or picking on her because I'm jealous, but honestly, I can't see what there is to be jealous of.

I  criticize her all the time when she's home, because I feel like that's the only way I can stay afloat or be heard when she's around.

"All that really matters is if she gets A's and B's in college." Dad said the other night when I mentioned this.

Where does this philosophy come from? It doesn't matter if she's drinking or smoking pot. Doesn't matter if she gets pregnant or passes out drunk. It does not matter if she ruins her health and family relationships, if she gets A's and B's in college.

I can't think about this anymore.