a girl tried to embarrass me at school

Today, at school, I just came into my classroom. I was kind late (ig??) 6+ minutes late tho. The teacher was talking and in my seat, there were 2 people sitting. A while back, I had this friend, aka my first friend at school way back.. but some girl who insulted me just stole her ( ;´ - `;) I mean, it's her choice if she doesn't like me and doesn't want to be my friend. So like, my friend went away and sat near that girl, so my desk had two empty chairs. And today my ex-friend and that girl's friend were sitting at my table. I wasn't like mad or anything but THAT'S MY SEATTTT!1!1!1!

And then I asked the teacher where I should sit and she said "This is your classroom, you can sit anywhere you want!"... Classroom? More like a place where people keep talking shit about me. Then I saw that girl grinning, and it was sorta sus. So I sat in some place where another one of my friends sat, and I just sat with my other friend. But when I placed my butt on the chair, that girl was like "Looks like someone's embarrassed lmao" or anything similar (P.S: I'm translating what they said to me in my language so it might not be accurate). 

She probably told them to sit in my spot to make me embarrassed. I guess her goal was to make me embarrassed, prolly delusional or shit. That girl did something similar a while back. Back when my ex-friend used to still sit with me, I saw her sitting in my seat with her stuff and everything. Then I asked the teacher the same thing and she told that girl to sit in her own seat.