Looks like it is growing very fast!? With the free disk space (~200GB) on the datastore, you may receive a disk space warning while deleting the snapshot. However after merging the deltas into the base disk, the snapshot will be deleted and you will get back the temporarily required disk space.
As a side note: Since the size of the snapshot is now almost the same as the provisioned disk size (you mentioned 150GB in your first post) you may also want to check the guest filesystem for free disk space.
André