AITAH for wanting to move with my cat?

I apologize if this post is a bit jumbled.

I (17F) am planning to move out shortly after I turn 18 to my aunt's place because of narcissistic family members. We have 2 cats, and one is registered and bought in my name. The problem is the cat I want to take is equally bonded to me, and my lonely stepfather (he himself is not narcissistic, but he permits treatment from my mother and brother).

My aunt is in the middle of putting one of her cats for adoption due to spraying and other behavioral issues. (For background info- he is kept in the basement for said reasons. I plan to move into her basement, and have my cat down there too.)

I genuinely can't part with my cat, but my entire family is heavily against the idea of me moving with her due to the fact she has bad anxiety, and that her absence would make my step-dad lonely (long story short, he is autistic and socially inept. If it weren'tfor my cat or step-sister, his only company would be my narc mother).

I'm aware that she, like any cat, would struggle settling into a new house that already smells like cats. But am I the asshole for wanting to take her with me? She was given to me a few years ago as an emotional support companion because of my severe anxiety and depression.

edit: I plan on going little to no contact with my mom and step-dad because of their narcissistic teaming.