Bully flirted with her and steadily brought her to the edge. To the point where your mom voluntarily spreads her pussy lips and begs him to fuck her. He fucked her in every part of the house. Still they couldn't get enough of it.
Your bully acted like he's your friend infront of your mom. Two visits to your house and now he's fucking her after drinks. Everyone in school now knows that your mom spreads her pussy for him.