Im being abused by my girlfriend and i dont know what to do plz help?

so today at school i was walking down the hallway and ninja pirate's with there girlfriends(making it a single and relationship problem) attacked me. they told me if i dont do what they said they would murder me where i stood. so my instict's kicked in and i did what they said. they told me to sing im a barbie girl kinda was weird but i did. they also told me to come to school tomorrow with a dress so i am going to. they also tried to goa google my smoogle himmer of course i told them to back up off my grill they did. is this weird for this to happen to me? what should i do?