Dishonest boss

I have been written up at work for "performance" related issues. I have made some mistakes, and I concede that I need to pay more attention to detail. My mistakes have been minor, I am an accountant. Spelling mistakes, wrong header, not updating my journal descriptions, and a couple of times not making the requested changes per my supervisors. While I agree that I can improve with regard to these issues... My boss is bent on making me look incompent. She has emailed me on issues that are clearly not mistakes, such as using wrong beginning balances..which is untrue, and easy to prove. And a few other instances where clearly no mistake has occurred. I have been reluctant to speak up because the one time I did, she would email and copy others on issues such as spelling errors, :recalls(autocorrect) instead of reclass, and very minor issues. I have a meeting tomorrow, but it am unwilling to sign the outlined offenses as is because some are untrue. I don't want to come across as combative, or make my work situation worse, but my boss is a liar. She is also not that bright. Her position came along with her tenure at the company. What do I do?