The snapshot file is 23Gig, and is definitely in use. Most of that is probably temp files that I created (in an attempt to fill the empty disk space with zeros to enable maximum compaction.) Reverting drops that down to 306 Meg, but then the VM will not boot, and goes into a startup recovery loop.
Note that I have used sdelete to aid in compacting my VMs for several years. My mistake was moving my sparse VM that had a max size of 75 Gig to a 76 Gig partition. I did not leave enough available space for system files and snapshots. Now I am trying to recover from that mistake.