favoritism

I'm so sick of my mom showing favoritism to some of the grandkids and not all of them.  Come to find out she bought Christmas for 8 out of 24 grand kids!   I am so done with her she has done this before and i confronted her about it, she said sorry but I don't think she is!   I just want to be done with her age is a liar and a shit starter and I've had it up to here!!!  Uggg!  These 8 kids are all teenagers!!  My daughter is 1 of the youngest and do you think she got something Nope!!!  I called my sister and she said her kids didn't get anything either, she told me to drop it it im upset, I want to be done with my mom!!!