How should I go about telling my mom (lives in Washington) that I want to move with my dad (lives in mississippi)?

I love my mom. I love my dad. I visit my dad every summer and winter and I live with my mom during the school year. I don’t like my moms husband. He shows favoritism towards his real children. My family in Mississippi is much happier so I’m much happier there. I mentioned moving with my dad once to my mom and she cried and made me feel bad. I wanna bring it up again but I feel bad so idk how to talk about it. (I’m 14)