Well said. I had a similar issue with my own manager last year. She decided to micro manage, moved the goal posts repeatedly, tried to blackmail me into doing her work, isolated me from colleagues by saying bad things about me, examining and criticising every piece of work I did, and generally being a bully.
I trained in the army, where pissing contests are the norm, so I have seen this before. I resisted immediately and consistently. This left my manager with two strategies to choose from. Either back off and lose status, or escalate. She chose to escalate. The more she escalated, the more I resisted. It is a risky strategy for her. On the one hand she is betting that I will relent sooner rather than later so she can have her way, and in return she will give me some peace. On the other hand, the more she escalates the more intrusive, abusive, unreasonable, and messy things get for both of us. The messier things get, the more people notice, and not in a "look how well she is managing" kind of way.
Meanwhile she made a friend at HR and told them all about this terribly unprofessional employee she had. Then I got a letter from HR requesting a meeting to discuss some concerns my manager had about my unprofessional behaviour. This is where documentation comes in handy. Try to get every decision in writing. My manager took great care to say verbally anything that I might use against her. The best I could do at that point is write her an email asking for clarification or confirmation. Then she either confirms it, sealing her fate, or refutes it, letting me off the hook, or she ignores it, implicitly accepting it. In any case, there is now a paper trail. Once she sees her request in writing, she usually tries to weasel out of it, implying I misunderstood and comes back with a much more reasonable request.
I succeeded to disprove most of my managers accusations by bringing up old emails. That took the wind out of the remaining accusations. Somewhere in this process my managers new friend at HR realised she had been hoodwinked and swap herself with someone impartial. Then things really started to improve. My manager couldn't conceal or undo some things she did while escalating. HR elevated some issues very high up the ranks. When busy important people have to fix underlings fuck-ups, they remember. They will fix things once, but not twice. My manager knows that if I am going to give up my job and get a shitty reference because of her, I will make it as difficult as possible for her and take her down with me. We have a much better understanding now.
Morel of the story:
- Get everything in writing. You might need it. In any case, written agreements tend to be self limiting and self enforcing.
- Resist firmly and consistently. If you waver once, you give them leverage.
- Things will get much worse before they get better. Find as much support as you can.
- Keep it clean. Let the other person lose their morel high ground if they choose, but don't follow them.
Finally, I would say do not give an ultimatum between X or leaving. I have seen people do that, and the response is generally "OK. Leave. Bye". Your company might start preparing for it, leaving yourself little room to negotiate. You can always leave after trying all other avenues, and finding another job first, but don't let them see it coming.