I also faced similar issue and was able to solve with post on apple discussions.
However follow these instruction carefully and make sure to have all backups in place.
Based on comment below, adding answer in post
sudo gdisk /dev/disk0
If you get any error messages at this point, report the error messages, don't proceed further.
You're now in gdisk interactive mode. Menus/commands are single characters followed by return/enter. So type ? and and you'll get the main menu listing commands. Type p and it will print (display) the current GPT. Since you have 5 GPT entries, you can't use a 1 for 1 GPT to MBR scheme like Apple does. The following suggestion is safe, but all hybrid MBRs are non-standard inventions, and therefore I can't tell you how Boot Camp Assistant or Disk Utility will react to this hybrid MBR should you decide to make changes later. What I can tell you is Windows, Linux, and Mac OS X themselves have no problem with this MBR scheme.
r go to the recovery & transformation menu
h create a new hybrid MBR
5 add partion 5 to the MBR
accept the default MBR hex code of 07
y set the bootable flag
n do not protect more partitions
o print (display) the MBR
You should have two entries. One type EE, one 07, with the 07 entry marked with * under Boot. If you don't, report back. If you do, write out the update partition information, and hope a power failure doesn't occur for the next few seconds...
w write partition table to disk
reboot. hold down option - you should be able to boot into either Mac HD, Recovery HD, or Windows.
I just tested this same five partition GPT and 2 partition MBR on a working system and the instructions above worked.
Note, so long as CSM-BIOS and thus MBR are required for Boot Camp instead of EFI booting Windows, we're stuck with flaky MBR problems, as well as the 2TB disk limitation for Windows boot disks.
Also, I filed bug ID 11980880 at bugreport.apple.com and referenced this thread.
It's probably still stored in a Time Machine local backup. Open Finder, browse to the original location of the drive you deleted, then open Time Machine. Go back in time to find the file, then right-click it and delete the backup of it. This will return the space.
Best Answer
File Clearing
As user2277872 mentioned it's probably a good idea to get a disk analysis application to find out what's eating up your disk space. A few good applications to start with are DaisyDisk, OmniDiskSweeper and Disk Inventory X, each available here, here and here respectively.
If you find no big files cluttering up your space, here's another link covering some things that might be using up your disk space that you may have overlooked: http://www.howtogeek.com/184091/5-ways-to-free-up-disk-space-on-a-mac/
Partition Resizing
However, if your 43 available GBs are on your Windows partition, no amount of file deletion on the Mac partition is going to help. What you need to do is resize the partitions.
Disclaimer: it's always a good idea to make a backup. In theory, no data should get deleted but things can always go wrong. Grab an external HDD and image your system onto it, or at least copy your important files over.
Boot into Recovery (
Cmd-R
on startup) and open Disk Utility.Select your parent drive for both your Mac and Windows partitions (assuming they're on the same physical disk).
Click the Partition button in the toolbar and resize accordingly. You may want to allocate about 80GB to Windows or more depending on how much you intend to use it.
Click Apply and reboot. You should be able to boot into your Windows partition now.