confused about how the son knew about his mom's affair [spoiler]
Did it have something to do with the scene where the classmates are tossing the guy's phone around and he's telling the one to stop looking at his photos 'cause it's using up battery? I found that scene confusing.
I think the son's character was acting out misogynistically: First he calls his own mom a slut when she won't drive him to where he wants to go, then he beats her affair partner to a pulp. Brutus complex.