What is Peyton refering to when she says "you made fun of my mom's death" to Brooke?

Hi everyone! In season 4 episode 15 named "Prom Night at Hater High" Peytons says to Brooke when they fight: "you made fun of my mom’s death Brooke. আপনি knew her, আপনি cried with me when she died and now আপনি use her as a মুষ্ট্যাঘাত line for a joke to hurt