How can I get revenge?

I want to get revenge on my classmates who conned my best friend into leaving me. I was friends with her for a year and a half, a few weeks later I told her she was my best friend, then my friends started saying that to stay away from her, and then some weeks later, she said to stay away from her and her friend who are my friends as well and my teacher said it as well and my parents are on their side and they say to not hang out with her friends as well. Now I only have only one friend from my group of friends. I want revenge on those people who betrayed me. Any ideas?