Often the most friends and family members can do when dealing with a narcissistic personality is to establish very firm personal boundaries, with clear limits regarding each individual's rights to make one's own decisions and to define one's own person. Encouraging the narcissist to take full advantage of professional counsel (described as support rather than "help") is always important.
You keep teaching them.
Celebrate !
Punch her in the vagina.
Dump him
The most unwanted characters are those with a Narcissistic personality disorder, and the way to deal with them is to avoid them.
Get out of there! You can't change them, so I move on to more sane people.
The best way to deal with a narcissistic mother-in-law is to "kill her with kindness." This method works on most people, by the way. Be as nice and polite as you can possibly be but don't engage her more than you absolutely have to. Remain calm and don't feed into her narcissism and neediness.
always have respect to your superior
call your manager and say she stole money from the store! hahaha
Suck it up and get a good lawyer. Also, read "without conscience". It illuminates how to deal with people like that.
You probably should have figured this out before you got married. Best advise really would be to get counseling, because that is a problem which will lead to severe difficulty.
Few people - especially if they are really narcissistic - take kindly to being called narcissists.