OK some great advise already on here, but for what it is worth I will add mine.
My Mother in law suffers (we believe - diagnosis is impossible) with Narcissistic personality disorder (NPD) and I recognise all of the manipulation, situations, feelings, fears and confusion you feel, as I have seen my wife go through all of it. I strongly suggest you do some research on the subject, and how to manage someone living with it.
A few KEY points. You are not responsible for your mothers happiness. It may be completely impossible for her to be happy unless she has everything her own way, and that is not compatible with actual real life, so you can forget that. Not possible.
You are however responsible for your and to an extent your immediate family's happiness (as far as possible), and there are things you can do to improve that.
We have cut off completely my Mother in law, and life is much much happier for it. This is also much easier on the other side of the world. Sadly my sisters in law in AU have not been in a position to do so, and they have suffered the consequences, as have their children. I wont say more than that, but people like this are very very damaging. In my view you are fortunate this hasn't already ruined your marriage. You already made the decision to move away, I suggest you know what you need to do next, but doing it is hard, and you need to balance the rational and emotional to do so. I wish you luck.