Your mom hasn't had sex in years. That's why when she caught your girlfriend cheating on you with your bully, instead of confronting them she joined them.
My girlfriend sneaks into my bully roommate's room after she thinks I'm asleep. One of these days I'll work up the courage to confront them, but for now, I jerk off outside his room to her moans!
You bully decided to celebrate the Christmas with you family, and your mom and sis really like their gifts