this might not be the case of what i will be explaining, of course, and he might really have taken it seriously, but if you apologised, it's just gonna go away.
however, i wanted to give some insight on what else could have happened -
you know, for a different perspective on this -
even though you might feel like he really took it personally and got hurt, sometimes there are situations in which an enfj might deliberately act as if has taken something that is a joke seriously and appear hurt even if he understands that it was just a joke and is not really hurt that much - it's like the enfj wants you to know that the joke was inappropriate, in his opinion.
or maybe it's just me, but sometimes i do act like that, for example, when my dad jokes really inappropriately in my opinion - i pretend that i didn't take it as a joke and ask him not to say such things, because i don't want him to do it again, since it might hurt someone for real - i've seen my mother really hurt due to his inconsiderate jokes.
it's like trying to teach the person some manners, limits - especially if it's someone who thinks is responsible for you (and supervisor is supposedly responsible for your personal growth) and for others with whom you might communicate.