Re narcissists and tantrums:-
"Given distance, or only transient and intermittent contact, you can get along with narcissists by treating them as infants: you give them whatever they want or need whenever they ask and do not expect any reciprocation at all, do not expect them to show the slightest interest in you or your life (or even in why you're bothering with them at all), do not expect them to be able to do anything that you need or want, do not expect them to apologize or make amends or show any consideration for your feelings, do not expect them to take ordinary responsibility in any way. But note: they are not infants; infants develop and mature and require this kind of care for only a brief period, after which they are on the road to autonomy and looking after themselves, whereas narcissists never outgrow their demands for dedicated attention to their infantile needs 168 hours a week. Adult narcissists can be as demanding of your time and energy as little babies but without the gratification of their growing or learning anything from what they suck from you. Babies love you back, but adult narcissists are like vampires: they will take all you can give while giving nothing back, then curse you for running dry and discard you as a waste of their precious time.
It is also essential that you keep emotional distance from narcissists. They're pretty good at maintaining a conventional persona in superficial associations with people who mean absolutely nothing to them, and they'll flatter the hell out of you if you have something they can use or if, for some reason, they perceive you as an authority figure. That is, as long as they think you don't count or they're afraid of you, they'll treat you well enough that you may mistake it for love. But, as soon as you try to get close to them, they'll say that you are too demanding and, if you ever say "I love you," they'll presume that you belong to them as a possession or an appendage, and treat you very very badly right away. The abrupt change from decent treatment to outright abuse is very shocking and bewildering, and it's so contrary to normal experience that I was plenty old before I realized that it was actually my expression of affection that triggered the narcissists' nasty reactions. Once they know you are emotionally attached to them, they expect to be able to use you like an appliance and shove you around like a piece of furniture. If you object, then they'll say that obviously you don't really love them or else you'd let them do whatever they want with you. If you should be so uppity as to express a mind and heart of your own, then they will cut you off just like that, sometimes trashing you and all your friends on the way out the door. The narcissist will treat you just like a broken toy or tool or an unruly body part: "If thy hand or thy foot offend thee, cut them off" [Matt. 18:8]. This means you.
So, yes, it's possible to get along with narcissists, but it's probably not worth bothering with".
I do wonder if you will ever be able to break free of her or whether you find that whole prospect far too daunting to even contemplate. She does not just affect you, its your own family unit that she wants to get at as well to use your children as narc supply.