What is the name of this so and so and where does he live?
You might start making some quiet calls to administration, EAP, or the employee assistance program, if any. The EAP should be able to start you thinking about push back. He cannot treat pregnant women the way you are describing, and they might help you to find some people to talk to about short term means to deal with the stress, and long term transitions away from this situation. Expecting 12 hours a day for regular post docs (and he probably is thinking 7 days a week), is excessive and probably unproductive. I have worked with or close too such monomaniac, egotists. The structure of academia is pretty tolerant
(as long as they are bringing in the big buck grants).
I think this situation is one that illustrates the need to transition most post-doc funding to training grants and with a lot more oversite on the outcome of the so-called training experience. You are not his cheap labor!
"You know I'm temperamental." "Yeah, 95% temper, 5% mental." - "Curly" & Moe Horwitz