Should I apologize to my friend?

I think you shouldn't be talking to them, obviously they talk on your back and trust me "true friends" won't ever do that, if you have the chance to meet knew people it will be great, get over them, and DON"T apologize, that is what they want you to do, don't let them to control your life (especially Emily). Try to get new friends, a true friend never is going to make you feel bad, guilty, depress or sad. I hope you can get new friends, and get rid of the old ones.