Disclaimer: We have strict labor laws here - firing is strictly regulated.

• I worked as little as possible, and just enough so he couldn't fire me over not working.
  
• I restricted all communication to factual replies, keep them as short as possible, then waited an hour to see if I could make the reply shorter.
• Time is your friend here, emotion the enemy. Don't let any emotion out, it's what feeds them. So I took the time to make my replies as emotionless as possible.
• Anything that was kind of judging his behavior should be filtered out.
• First thing to do when replying to a mail is to remove all email addresses to you can't accidentally hit "send".
• I never replied within two hours unless there was something I really fucked up. Preferably I took four hours or more.
• I regularly fucked up. I really fucked up many things as I was totally not motivated, and didn't care anymore, but making mistakes is not a reason to fire someone here. So if I corrected my mistakes, I was good.
• Best time to send out mails is 15 minutes before the end of the day. He would reply in the evening, forget about it the next morning.
• He could send mails with outbursts of emotions about things he didn't like in the work I did, but then didn't tell me to how change it or what to do else. It was just an emotional outburst. Normally I took the effort to think of what he wanted. I stopped that. If he didn't tell or ask "do this" or "fix that", I let it pass. He forgot about it and that was it.
• If he got mad about me not acting on his mail, I acted confused, wrote that I misunderstood and would correct my mistake immediately. I appologized, admitted my mistake fully, and played dumb. I then did do what was asked and let him know by the end of the day. If he didn't like it, he would reply that same evening, but the anger would be gone the next day when I would read it.
• I kept a log about everything that happened. It didn't make a lot of difference in my case, but you should do it.
• If you keep notes in your phone, use an alias instead of his name (and coworkers), so he doesn't see that you write about him if he might walk by.
• We had several talks about me leaving. I recorded all conversations with him without him knowing. That is legal here.
• You can use your phone or a usb recording stick. It's a USB stick that has a microphone and a record button. Cheap and effective.
• I recorded all phone calls using Boldbeast Recorder (Android).

Of course this was an end-game. We both knew we wanted to end this, but I wanted an exit fee, and he didn't want to pay. I'm out now, and I'm glad about it. Working there was one of my biggest mistakes in life.