Why do some people do everything and say everything just to hurt your feelings?

I am so fed up. I can't take this anymore. My aunt has been destroying me since I was young. I don't know why she is so negative when it comes to me. Her words aren't even that mild but extremely mean. She is like mad that I was born. Her toxicity is too much that my self-esteem has gone to extreme lengths for the last 10 years.....I just can't take her anymore...I've been detaching myself from her but my mom always brings me close to her...sometimes I wish she just dies....I mean sometimes when says something really insulting I wanna cry deep down but I just feign to be not affected at all...