emotionally abusive parent

I've suffered through mental and verbal abuse from my mother for as long as I can remember. I have moved across the globe from her and am able to completely cut her out of my life but I can't seem to get her out of my head. I keep hearing all of the things she has done or said to me and I can't get rid of it. And she always finds a way to get in contact with me and guilt me into letting her back into my life and I just can't feel okay anymore. I feel so weak and helpless and I don't know what to do. Please give me any advice on how to end this horrid cycle.