AITA for not wanting a relationship with my sister?

My sister and I didn't get along well growing up. When we were younger, we often used to fight over small things. After seeing how well all my friends got along with their siblings, it made me realize how broken my relationship with my sister was. At that time, I was 14 and my sister was a few years younger.

I tried to talk to her and often asked to hang out with her, but she was never interested in spending time with me. We never hung out and every time I asked her if she wanted to spend time with me, she'd say no and make up an excuse.

When I moved out at 19, I decided that there was no reason to try to reach out to her anymore. She would never want to do anything anyway so why would I even waste my time trying? I still see her at family gatherings every year but we don't talk much and have nothing more than a cordial relationship.

I'm now 21 and she's 18. Recently, she has tried to reach out to me (by either texting or calling me). She would ask me how my day was and start random conversations, but I honestly have no interest in responding her with anything but short answers. After a few weeks, she finally asked me why I didn't want to talk to her and why I was being cold hearted. I don't remember the entire conversation but it included:

Me: We were never close growing up so why should we have a relationship now?

Sis: Because you're my brother and I love you.

Me: I'm sorry, but I don't trust you and I have no interest in having a relationship.

Sis: Stop being cruel.

Me: I'm not being cruel. That ship has sailed and there's no going back. If you really wanted a relationship, you should have cherished it before it was too late.

She started crying and begging me to give her another chance but I didn't change my mind. A few minutes later, my mom called me and said I was being an a**hole to my sister and that I should just make up with her. But I don't think I'm in the wrong. It's not my fault she was distant to me for so many years.

Am I being unreasonable?
AITA for not wanting a relationship with my sister?
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