Should I tell on this girl?

The problem will never stop unless you do something to stop it. The safe way is to go to the dean to get this resolved. I really do not think that if you tell on Jess that you will be socially disgraced, but that really depends on how many people like you more than they like Jess or Fatima. Your popularity will not suffer if you are not like Jess, if you are nice to people, if you are not expect your popularity to decline. But be aware bullies, like Jess are not to be trifled with, they are serious. Once, I let a bully push me around, eventually they threatened to kill me after school in the middle of cl in front of the teacher, they didn't even care that they got caught! Don't let it happen to you, tell the dean, get the problem fixed, and release the tension between you and Jess. Good Luck.