This recently happened to me as well. I realised immediately what was wrong once I had released the spool to remove the film. Of course, I had to dry the film before I could reload and re-fix it. But there seems to be no harm done. AFAIK, the emulsion is quite tough when dry, so your man-handling it should not have done much damage even though it was only partially fixed.
You can do a drop test for fixer exhaustion. I think there is a recipe for the test solution in the Darkroom Cookbook, but it should be on the internet as well. A film should clear in fixer within about 90 seconds, and you can extend that to 5 min to be absolutely sure everything is out. If it takes longer than 90 sec to clear, start to suspect your fixer.