Any advice out there?

Hey y'all! I'm new to teaching and am a bit shocked at the "drama" that goes on in and out of the classroom. I teach at an LVN program and the majority of our students are non-traditional (have families, jobs etc..). What I'm noticing is that there is alot of cliques that have been formed, back stabbing, gossiping, attitude problems etc.. We have had incidents of cheating (students were expelled), bullying by the entire class of one student, disrespectful comments towards instructors and threats made towards instructors. I know, this all sounds horrible. This is not the majority of the students, just a few, but you know the saying...one bad apple... As the newest instructor (3 weeks) I have been very strict, established rules and expectations for the classes that I teach. My question is, what can we do about the behaviors that have been allowed to continue but are not acceptable? Some of these students have been allowed to act this way for almost a year without any consequences being given to them. Any advice is greatly appreciated!!