Q: Force quit boot camp while partitioning, HD memory reduced.

The simplest and safest method to get your disk space back is

1. Backup OSX and all your files - Use Time Machine to back up or restore your Mac - Apple Support .

2. Boot into Internet Recovery (Command+Opt+R) - OS X: About OS X Recovery - Apple Support .

3. Click on Utilties -> Disk Utility and Erase your internal whole disk.

4. Restore OSX and your files - Use Time Machine to back up or restore your Mac - Apple Support .

This requires a separate external disk which can accommodate TM backup - Backup disks you can use with Time Machine - Apple Support .

There are fixes using Terminal and diskutil commands, but a backup is still required. The Diskutil commands will just build the Fusion disk faster and can be done in Internet Recovery.