Do people start caring less about you when you get older?

Like when I was 7 when my mom abandoned me, people felt so bad. I through temper tantrums but now I’m almost 18, my friends and family are telling me it get over myself and move on. My older half brother said I’m not a little kid that cries for mommy anymore, she doesn’t want you or never calls you so forget her and move on. Even my best friends are getting tired of me talking about my mom. I few times I got told I should leave if I keep talking about my mom.
I cry when people insulted me as a child and my dad and siblings stood up for me but tell me to stand up for myself and stop crying. Now an an adult nobody stands up for me anymore. They told me I need to start standing up for myself and they won’t always be around to stand up for them. My aunt screamed at me and my aunt and uncle didn’t stand up for me. My aunt has NEVER yelled at like that as a child.