My sister took my cat, came back saying he “ran away,” refuses to tell anyone where, and I genuinely feel like I’m about to lose my mind.

I don’t know how much longer I can hold myself together.
I feel like I’m seconds away from doing something I’ll regret because the rage and helplessness are becoming unbearable.
My sister took my cat to the vet. She came back saying he “ran away.”
That’s it.
She refuses to tell me which vet. She refuses to tell us where it happened. She won’t tell my dad. She won’t tell anyone. Every single time she’s asked, she either ignores the question or changes the subject. The only information I know is the clinic was in “ghobra”.
How the fuck am I supposed to look for my cat when the only person who knows where he disappeared refuses to tell us?
Every minute that passes feels like another nail in his coffin. I keep imagining him terrified, injured, trapped somewhere, or waiting for me while I’m stuck in this house with someone who won’t even tell me where to begin looking.
Then she sends a message to our family group chat saying, “Here’s my name and my ID number. Go report me to the police.”
Who the fuck does that?
If you’re innocent, why are you refusing to tell anyone where it happened?
I grew up in a severely dysfunctional family. I believe my mother has strong narcissistic traits, and my sister has always been the golden child. She can do no wrong. She never has to face consequences. Reality bends around her. Everyone else is expected to accommodate her, clean up after her, and keep the peace.
Now my cat is missing, and somehow I’m the one everyone expects to regulate my emotions while she sits there withholding the one piece of information that could actually help us find him.
My dad has stopped speaking to her.
My mom has stopped speaking to me.
I feel completely alone.
I’m questioning everything. Did he really run away? Is she hiding something? Was there even a vet? Why won’t she answer the simplest question?
Nothing about this makes sense.
I’m trying so fucking hard not to lose it because I know acting on my anger won’t bring my cat back. But I have never felt this trapped, this powerless, or this close to completely breaking.
What would you do?
Would you report this to the police?
Would you start calling every veterinary clinic?
Is there anything—legally or practically—I can do to force her to disclose where my cat was last seen?
Because right now I feel like I’m watching my chances of finding him disappear while the only person who knows where to look refuses to say a word.

Also I’m Omani.