lna needs advice on 'toxic'co-workers

I have worked for just over a year in a nursing home. Started out great, lots of change in management, now I'm frustated with the lack of teamwork and dysfunctional communication. I have been vocal, we've had meetings but the lna's that have been doing this for years think I'm negative and I've been told if I don't shape up I can look elsewhere! The new management doesn't want any waves and agrees. I'm heartbroken and discouraged. How can I work at this place and be the good little quiet robot they want me to be without being resentful?