Control through fear

This is one of the default setting my wife and mother of my kids employs in the day to day running of family life.
She is a lovely, very hard working person. Stereo-typically oriental personality I guess you could say.
All the positive personality traits are however coupled with several negative (standard issue human). She is a control freak and has always had a temper. I have learnt to dampen the bad temper when it makes an appearance and we as a family have learnt to deal with it. But there is no denying there is an element of living in fear, and of her using it to control things.

Examples:
An obvious one (directed at me) was the “…if you leave the next time you see me and the kids will be at our funerals…” to stop me from moving out!
The not as extreme (directed at the kids) “…if you don’t do ________ I will hit you…”
My daughter who volunteers at the local petting zoo every weekend and lives for her volunteering day, was recently inconsolable when she was told “…if you don’t do _____ you can never go to the zoo again.”
There are tons more examples of various degrees of gravity that I can’t think of right now.

None of these consequences are every usually carried out but I cannot comprehend why on earth someone would deliberately threaten things like that just to get things done the way they want them done.
One of the biggest reasons I haven’t left yet is not being able to leave my kids in this environment. I am not saying it would be a bad environment (she is usually a good person and good mother). But there would be occasions when the monster comes out, and what if I am then not there to mitigate? My son is soft and calm and he will “conform” but my daughter can be stubborn and hard headed. When mother and daughter collide it’s dramatic and neither gives an inch. I fear what could happen if I am not there. I fear …