They all hated you because you are quirkless

Bakugo : wow 😒 why are you still here?

Momo : ya get away you quirkless freak

Iida : guys please be quiet. This is not how you treat your classmate! 

Deku betrayed you because he wanted to be with them

(Not to worry you are the teachers and heroes favourite and Iida because he want to be a good leader. He is the only one that is kind to you. You can trust him)