My mother in law constantly nags at me and goes out of her way to show me how unhappy she is with me! I do my best to help her around the house but there is always something she manages to pick on! I get so frustrated at times and I try to speak to my husband about it but he does his best to neither listen nor do anything about the matter. I'm worried and I do not know if my marriage will last. . .

I would never consider living with parents and in-laws because no matter how good our relationships are with them, conflicts like what you'd describe would happen. When there is a dowager empress, the new one will find it hard to rule in peace, they say. I remember attending a marriage course years ago and the instructor says that if the MIL is difficult (usually is), and the son doesn't want to do anything about it, you can try going through the FIL. FILs are generally easier to talk to. For example, in your case, I would tell the husband and tell him to talk to his dad about his mom's behaviour. If all else fails, I agree with Tresa, make the decision to move out and have your own space. Sometimes even the biggest country cannot hold two queens. Good luck!