Why do people tell me to move on with my life from my mom?

My mom left my dad and I when I was 7-8 years old. I kept trying to reach out to my mom but she keeps rejecting me. It hurts. My dad said I need to stop calling her and I need to go on with my life and I don’t need her. I haven’t seen her since 2010. He gets hard on me when I’m dwelling in the past and he isn’t letting it happen. Not on his watch. My dad can be too tough sometimes. I hate Mother’s Day because people talk about how amazing they’re mommies are. I don’t have that. Nobody says anything about my mom. My half siblings (who are grown and in their 30s) said I should appreciate our aunt for stepping in to take the mother role and give her the Mother’s Day gift. My brother said I have know idea how much I mean to my aunt and I’m very special to her. They also said why waste time on a woman that doesn’t want me? My aunt admitted that I am her favorite niece out of all of them. My sister is her second favorite. I’ve always envied my siblings because they have an amazing mother. I want my mom! 😭😭😭😭😭😭😭