I slept with my groupmate at university and worried that he will tell everyone, how to calm down?

I slept with my groupmate at university, he’s 35 and older than me. I asked him to do STDs test, but he said “we’re just friends, if you care that much do it by yourself”. I blocked him after. Now I’m worried cause I also told him to not tell anybody about that, but how I noticed now he doesn’t like when you ask him something to do. What if he will tell everyone because he’s mad at me and will destroy my reputation?
And we have same classes once a week, and I have to see him every week and be worried about our situation.
And also the way he reacted about STDs test also so suspicious, and I have to do it by myself. But I’m international student and don’t have much scholarship and support and I’m really scared.
I slept with my groupmate at university and worried that he will tell everyone, how to calm down?
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