me and my girlfriend broke up and i need advice

just for background information, me and my ex were together for around 8 months. and we have some differences that kinda messed up our relationship a bit, but we always got over it. until now. so basically im polyamourous and shes not, im autistic and i always make sure to tell her that she needs to communicate when shes upset (which she does sometimes but usually i always get upset and think i did something wrong), and if i accidentally make her uncomfortable she usually doesnt tell me so i just get confused when shes mad at me.

So the reason we broke up is because i asked her if i could be in a poly relationship with her and one of my friends (which i am now dating). When i mentioned it to her, she said something around the lines of "i dont want to do that" and i said multiple times she isnt forced to do it, she could just say no and we could move on. But then she just said that she wanted to break up because she didnt like the fact that i liked someone else also, which shes perfectly in the right to say that. but for some reason she doesnt want to stay friends (if any of you guys could tell me why she possibly wouldnt want to be friends anymore that would be amazing i suck at relationships) and she says "i cant be friends with my ex if we were together for 8 months that sounds silly" even though she said before if we ever broke up we would still be friends.

i just need advice what to do here, how am i supposed to move on from this? we have a class together so its gonna be awkward especially becuase we all hang out with eachother.