How do I know if someone is planning on killing me

Hi, I'm a male 15 years old, my one friend also a male likes me. so now every one at school is calling him gay so now he is starting to say that he will so us that he is not gay by hurting me and last night he said he told my one friend that he is planning something big for me, and his behavior has started to change not to me but to every one like he is just weird and he is making threats.

You need to let an adult who's responsible for your and his safety (parents, teacher, principal, guidance counselor, etc.) EVERYTHING that is going on so they can determine what to do to ensure that everyone stays safe.

Have you told anyone at school like the principal or someone?