i haven't been diagnosed but i too think im autistic, realizing this made me understand why i struggle to make friends. i always say i didn't really 'make' my friends in highschool, i feel like they just found me. idk. i didn't make any friends at college because i was too shy and nervous to speak to them. i didn't know what to say. but yeah, i understand a bit how you feel on that front.
your old friends/housemates, they do sound cold. you had every right to move out if you didn't like living with them. thats their fault, if they weren't as you described, you wouldnt have moved out leaving them without another roommate. i agree with the above reply, ignore them completely. if they wanna walk around being uncivil and possibly talking about you, let them! focus on yourself, your education, and anyhting else in your life! you can flourish and grow whilst they stay negative.
i understand, though, how hard it can be with anxiety, like no matter how much you want to think about anything else, you will still think about how they might react at your next class together.
as for making new friends, again it can be difficult, but i say go for it. talk to more people in your class or like the person above said, do it online.
i think overall though, first and foremost, take care of yourself. block anything out and focus on you, and then things hopefully get better for you. i hope everything starts to look up for you and get better.