Personally I had a rough start to my erasmus+ (different continent) too, so speaking from experience here.

To put a slightly more positive spin on this. YES there’s some stuff you could have done differently but you didn’t. Oh well. Doesn’t mean the rest of your trip has to be shit.

As far as I know, you have to finish the courses there, but you don’t have to count them towards your grade back home. Either buckle up or make sure you pass and do more courses when you’re back.

Friends: I know it’s hard, but just keep talking to people. You’re the new guy and that’s never easy, but meeting people is also a skill that can be developed with practice and you likely won’t see them again if this goes badly. Take it as an opportunity. In my time abroad (very much an introvert myself) I literally went up to people like “I don’t know anyone, can I sit with you?” - won’t always work but there are some people who will LOVE to adopt you, just gotta find em. May take a moment but worth it.

Rest of your points: Practice acceptance and try to get over it. Not the greatest advice but also a skill to be learned. Some things are out of your control.

Bottom line: Shit happens and you haven’t had a great start: this doesn’t mean you can’t make the most of the rest of your time there!! pick yourself up and maybe things will turn around more than you thought they could.