I am not the writer, so they are the ones that should defend themselves. However, the janitor is a half-witted guy, meaning he is mentally-retarded. So he is not gonna tell everyone. (If he sees anything on the cameras), he will show it to Donna. Donna may (or may not) confront Karen. If she does, then Jacob will spill the beans about his relationship with her. So Donna is kinda in a vice. But I would like to see their confrontation. Karen may say that I did it to protect your daughter. But from now on, he doesn't need a girlfriend, because he has his mom ...
As I said, I am NOT the writer, so these are just speculations and hypotheticals.