It's really important to remember that the grade boundaries are dependent on how well the general student population doing that exam have done. Those exam papers were killer for almost everyone so the grade boundaries have to be low. It's likely we're looking around the 2018 grade boundaries so something like 60% for an A and around 50% for a B. That's just my guess though.
It's all over now so just focus on your other exams or if those are over, try to forget about it.