Toxic family member

I am writing this because I just need to get it off my chest. A year ago, I decided to estrange myself from my extended family as I have never really felt comfortable nor appreciated by them. There is one aunt who, since childhood, has made harsh/cruel remarks about myself in all life aspects which affected me growing up, specially when I was a teenager as it affected my confidence.

Also, something that really hurt was the fact that she hated my cat and she would always make sure to let me know about it. She would always call him "that ugly cat", which really and deeply hurt because he was one of the most important aspects of my mom's life and mine, he was family for us two. When he got I'll and my mom and I were fighting so hard for him to recover she would always be mean and never showed compassion.

After he passed away, as you can imagine, we were both devasted as we did not only lose a pet, we lost a family member. However, she never said sorry for your loss and never let us know if we needed anything. It had been awhile since I didn't attend family gatherings and such because I couldn't bear listening to her talking bad about my cat. I stopped celebrating Christmas with her, which we had done ever since I can remember. But, to be honest, it was a relief. I love Christmas, but every Christmas dinner was a nightmare because of her cruel remarks. So, when my mom and I finally decided to celebrate on our own I finally felt at peace.

I must add that I usually kept sending the typical happy birthday, merry Christmas, mother's day, etc. messages to her as a way of being polite and guess she did the same as these messages are important for our family. Nevertheless, this year she did not wish me a happy birthday claiming that she had been busy and forgot. But, I also think that she might be jealous as I have achieved more compared to her own children, who are almost 10 years older than me, and she cannot say anything "bad" anymore about myself.

However, it felt weird as my mom always remembers her children's birthdays and such. I know this may be stupid for some, but for me it was important. Yesterday, it was her birthday but I didn't feel like wishing her a happy birthday as, even if I moved out of the country, has never even asked me or my mom how are we doing. So, I think this officially cuts all ties. I can't help to feel weird but relieved at the same time as this family relationship has been really complicated for almost my whole life.

Have you ever been through something similar? Do you have any advice?