Aids is your smallest worry here. Pregnancy is the biggest.
Dont worry too much about that just yet. First you wear right to use condom during sex and rhese things happen.i would ask you how long ago did thjs encounter happen but no matter what its not the end of the world. Go seek an advice of aedical professional. They might have solution for you.i could say you should take a post sex encounter drug anf you're fine but you still need to check yourself for std.so cover your bases and dont do thay again. Know the person and set boundaries too in the bed section if need be