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.
Celebrate !
Suck it up and get a good lawyer. Also, read "without conscience". It illuminates how to deal with people like that.
Punch her in the vagina.
It isn't pretty
The usual response of a narcissistic husband is to not want his wife to leave - because he can't imagine the thought or image in his head of any other guy being intimate with her, in any way. It is a big problem, on his part. Your task is to ask the quesiton, "Am I better off with him or without him?". The answer to this question should drive your actions (rather than any guilt feelings you may have about what your husband is left to deal with).
Dump him
let him have his time with her but you stay away and dont allow him to abuse you
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.
Beat you with a shoe and tie you to a bed.
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.
That's tough. You can try talking to her. But, most importantly you need to remember one thing, You married her son not her. Dealing with someone like that can be very frustrating. If your husband will not stand for you, you need to. Tell her how you feel.