So I have a younger sister and a cousin who can pretty much be considered my sister also. She has been living with us since we were little. They are both 20. I'll call her Kay for the story.
About a month ago my cousin went to visit her friend that stay an hour away at a college I graduated from...okay cool. This was a Friday night and she was planning on staying until Sat/Sun. I'm always checking on her and not having heard from her since earlier that Friday...it being Monday I felt something was wrong.
I'm at work on Tuesday...and she leaves a voicemail crying.

Once Kay said the first word...I knew something wasn't right.

So I told her to come by my place after work. She tells me the whole story.
Kay was at a small party at her friend's place. She was feeling tired/buzzed so she went to her girl's bedroom to laydown. Some Brotha she was talking to prior that I warned her was a player...I guessed he snuck in and started kissing on her. Kay told me she was groggy and then this dude tore her panties off and stuck it once...she became alert and pushed him off. He stopped and apologized. She immediately drove back and told her girls what happened...apparently they knew he had a baby momma and some other drama...but they didn't want to ruin him trying to talk to her?

I was asking her in detail what went down. My first instinct was to call the police...but the incident happened near 4 days ago so that was seeming futile. I was them going to tell my dad, but she had me swore not to tell a soul nor to hunt this dude down and react.

I know if I told my dad he'd prolly shoot the guy and never trust Kay again...as he is a paranoid (rightfully) over the girls more than me.
So I took her to the clinic and doctor to make sure she was good. I saw the nurse I saw nearly 6 months ago with my incident and she said some slick comments.

Should I have told my dad or the police? I haven't told anyone since this went down in December. If I had told she'd prolly not talk to me for a good minute and I wouldn't be able to keep a close eye on her. I knew she had my back when I told her to keep a secret about me getting burnt and my pregnancies with various hoodrats. But I feel as though as I betrayed my parents by not telling them.
I gotta get this off my chest, but IDK.

Please ask any question if this story seems scattered and unclear.