Why is he being this mean? Any ideas?!?

I sit with my ex on a table with two other boys and another girl.The teacher teacher made us sit there.He keeps going on about how my best friend made him go out with me and how im ugly,terrible,stupid.Every single fricking lesson they chuck horrible verbal abusive comments at me,I atualy think hmm I wonder how many I will haave this lesson.All the boys on that table make me feel like a right idiot. One said ewww you just spat on the table?!! I don't want to be me,I hate me.I can't ask to move because they will think I'm really weak.