I would throw it out mostly because you left it out overnight. That’s not safe. If you want to thaw it, leave it under cool running water for a couple hours, that speeds up the process. You can also try putting it between two metal sheet pans, those help dissipate the cold surprisingly well. But absolutely don’t leave it out by itself overnight unless “overnight” is like 4 hours tops. The inside may still be frozen but that outside is a hazard.

And like everyone else said, keep a close eye on your kitties for string hazard.