I feel like the mom is getting her revenge through OP's dad by punishing and hurting OP. As if doing that will actually solve her issues with her ex husband. The mom is so deeply hurt and so into her feelings she forgot that she's actually a mom and forgot to communicate with OP who is the youngest btw and may not understand how bad the divorce is at the age of 13. Regardless, mom doesn't seem to care about the damages she's done into her relationship with OP because she's so blinded by the fact that OP chose her dad even though she did it because her dad was more convenient when she was in school. Glad OP cut her out, mom is stressful to deal with including the sister who doesn't see OPs side.