Basic Instinct - Ending

[Nminyy]

I know it's rubbish, but I wanted to ask about the scene at the end. We see the ice-pick under the bed of Sharon Stone's character. Does that mean she was the killer all along? I thought it was clear the other lady was the killer? Or are there too ice-pick killer ladies? I'm not watching it again to find out.

She was the killer all along.

Yes, I assumed it meant she was the killer.

Yes she was the killer, was there a basic instinct 2 where she killed someone else or did I dream that ?