MBP Hard Drive suddenly Filled up, now only starts in safe mode
On deadline, of course, my hard drive suddenly filled up and crashed. On restart it loads a log window and says it is unable to install the OS and I can shut down or restart. It runs in safe mode, and from a back up. I've moved off tons of files so there is 39gb free, but it won't start up. How do I repair the OS? Booted from a back up Disk Utility found no errors.
MacBook Pro 15", 10.13