I'm going to choose to change my name even though it will hurt my mother
What will happen after you change your name that's going to upset her?
She won't be able to call me by my old name anymore.
It's your choice to go by whatever name you want.  That being said, you may wish to placate your mom by including her in this new naming process?  I hope that's a good compromise!
Shut up bitch. I don't want to make compromises.
I am sorry if that upset you but I agree you do have the right to name yourself whatever you want but you need to understand that she will be upset. Give her time she might accept it later.