djackgirl, you're in a toxic relationship. Take her to the back and shoot her.
All three above are absolutely right. Ditch the bitch and get an author who has not failed Human Decency 101. I think betas deserve credit for the job they do, and I make sure I include at the very least a thank you line at the end of every chapter they proofread for me.
Also, ApolloImperium is right. She plagiarized your work. If you can somehow use that to screw her over while you ditch her, all the better. She deserves it for being such a fucktard.
I sincerely hope you'll find someone who'll treat you right and help you get over this awful experience.