Certificate at risk

I am a CNA. I reported for work today and clocked in. I then walked to my permanent assignment and saw another CNA there working. I immediately walked over to the DSD office and asked if the CNA I saw was working my assignment? DSD said yes. DSD said she was helping us out and she wanted to work that assignment. She told me I was going to be sent elsewhere. I immediately told her I wasn't accepting being sent elsewhere and that I was leaving. I also told her I would write my resignation letter. She told me if I left she was going to report me to Sacramento for patient abandonment. How was I abandoning my patients if my assignment was given to another CNA. I never received a report on the patients I was going to take care of. Everything happened at the beginning of my shift. Reason I reacted that way, was because this facility over works their CNA's and we are always understaffed. I have become ill with stress and anxiety. I couldn't take it anymore. I couldn't provide great care to any patient working under these conditions. Everyday is a different problem. Also, a new person quits everyday. It wasn't professional at all, how I left, but my health is also a priority. Has anyone experience something similar? If so, what do you think is the outlook of my certification? Please advise