Yup...as others have already said...you're pretty much out of luck. The Bitcoin is gone and there really isn't much you can do. If you want, you could probably trace the coins through the blockchain and maybe get enough evidence to pursue legal charges but it's likely you will never get the coins back.

Consider this an expensive lesson and read some guides on properly securing both your computer and Bitcoin. As society advances into the age of cryptocurrency, internet treasure hunting is going to rise alongside it.