How come my grandma argues with all the time?

well she always has something bad to say like u looked like crap, u look depresed, yada yada yada. i am so sick and tired of it. when shes in public she doesnt even say anything but when we get ome she attacks me with bad launguage about myself. some times i tell her what she says and she just doesnt giva ****. she also blams me for alot of stuff that happens to her. the things she says is so hurtfull it just makes me wanna give up on life cuz if i have to live it like this whats the point of being born and living? what can i do? i cant go to my moms cuz my grandma has custody over me