Allegations against RN-what would you do?

2 CNAs and 1 LPN wrote false allegations against me and turned it into the DON. Just a week prior, I had finished and gave evaluations to 8 co-workers, CNAs and LPNs. All of them got overall great evals, with exceptional and outstanding marks. I made great comments on their strengths. I wrote for one CNA the need to improve on attitude during shift change (not to yell and argue at previous shift ). 2nd CNA, made comment that she needs to improve on teamwork. I made a comment to an LPN that she needs to get her regular duties done before the shift is over (she tends to do her homework half the night and BS with her co-workers). All three still got over all great reviews.

The false allegation by all 3 is that I do not answer alarms, but instead go get them to answer the alarms. That is not true. I have never refused to answer an alarm. In fact, I am the one who usually gets there first. The DON wrote me up. I told her they lied. She said no they did not because several of them turned in the same statements. I was told by upper managment that this would probably ruin my career. For over 10 years, I have had great reviews and no write ups as a manager of my shift.

I keep witnessing the staff I manage to not give good care, ie. sit around, start their rounds late, not answer alarms or lights in a timely manner, not finish their rounds(ever though they say they do). I am in fear of writing them up because I know they will write false statements against me again. These same co-workers tell me that I am the best charge nurse they have ever had. To me this is a crazy situation I am in. I am looking for a new job.