I have a manager that continually lies.
She became our manager about 8 months ago. I started at the corporation two weeks later. I'm 28 and relatively new in my profession. The situations where she lies are numerous and included in practically every interaction, but I will describe just a few so that you can get the picture.
She constantly says things like "Colleague A says you are lazy" or "Colleague B said you botched Task123" when you are alone with her. None are remotely true and we learned not to speak to her about anything, but it took us a month to realize she was playing some divide and conquer game among us.
After a very successful project, the manager ditched our points because we didn't do some tasks that didn't exist. When confronted, she replied that these were "hidden tasks" and ditched the points anyway.
She would accuse me via email of failing tasks assigned to my colleagues or even other departments. To quote the style of emails: "We have to rethink your performance bonus (25% of my salary) because YOU did so badly in Task5432". After several such situations I escalated this behaviour to higher management, but nothing was ever done. Since then she refused to put anything she says in email. She still comes to say these things to me in person, though.
After the first 3 months I had an assessment meeting and I asked about a laptop that was promised to me when I was signing up. I half expected some bs about cost-cutting and waiting another month, but she just asked me "Do you have it in writing?" and literally laughed in my face.
My friend was planning a vacation, and the manager kept dodging the approval for 3 months. After the matter escalated, she finally agreed 2 days before the planned date, refused to accept any changes (these are the dates in the application form, these are the dates she is approving) and when my friend said that she was unable to organize anything at such short notice, she was told that she could stay at home "like normal people do".
In my second performance review 2 weeks ago (again, closed door, no witnesses), after listening for 3 hours about what a bad and sub-standard employee I am (all my customers are super happy with me and I have exceeded all my targets), she wrote down in her report that during that conversation I said that the entire company is a bad place and that it is misusing and abusing its employees. I didn't mention a single word about the company (good or bad). When I objected that this was not what I said, she told me that "it doesn't matter". I reported this to the HR, but nothing has been done so far. They asked me to make a formal statement, which I still don't know how to formulate.
Most of the team already resigned and I have just handed in my resignation (in electronic form because with another colleague she pretended she had never got his), but I have a 4 month notice period and I am already a nervous wreck. My colleagues warned me that it's going to get worse. I can't focus on anything and I am afraid that my tasks will be affected. I take pride in my work and would still like to perform well despite the circumstances.
What steps can I take to protect myself and others from this manager?