It is difficult to diagnose personality disorders. If they do have Narcissistic personality disorder there is no good way to deal with but keep praising them. Personality disorders are difficult to treat.
From your description it seems like it is difficult for you to freely express your opinions and concerns without being criticised and that it goes to extremes where your husband and in laws seem to threaten you - as you said. Otherwise, I will be given the command to just leave the house and end the marriage. This scenario is not conducive to long-term relationship. If you do not take any actions now it is possible that it could go on forever and may become even worse. If it has been happening for 2 years and not changed it is unlikely to change much in future.
Keeping these aspects in mind, I suggest that you talk to your husband clearly as to what you are concerned about emphasizing how you feel. If he does not seem to understand the seriousness of the facts you might have to take other steps.