Prom w. Mom!

So I'm a sophomore and my friend is a senior. She asked to prim since I'm new to the school and we're friends. My mom agreed so l started looking around online. Me and my mom were supposed to go to the mall and try on dresses. So today I texted her in school and asked if she wanted to go. She said yes. Then turned around and said no I don't want to try on no damn dresses go with devyn (my cousin) and she said my grandmother wouldn't watch the kids. So I 2as hurt and upset and started crying because I found out that she only said no so she could go to her 'bestfriend' house.

So I'm like you can't go with me because she won't watch them. But you can go over there. Am i being childish or what.?

P.s me and her don't have the best bonding relationship so this was supposed to be special.