OP I can understand how frustrated you would feel in the situation, but your options are limited. I've seen both sides of a similar situation as my mil currently has one of sons, the wife and kids living there for last 6 years. Thankfully the son and wife are now both have jobs but for a few years both were unemployed and being supported by mil.
I think for your own mental health you and your husband should try to move out. You mentioned your husband hasn't been able to find a job since graduating- he needs to get a job even if it's not in the related field. The longer he is jobless unfortunately the harder it will be for him to get a job in any field.
What type of degree does he have? Sometimes you need to start in not so great jobs to get to your desired job, as long as he gets a job that could be the first step in getting a place of your own.
From your mil's perspective I can see how things are frustrating for her. Are you and your husband contributing to bills, food etc around the house? Also it makes it hard when your definition of clean differs. I think while you're living with them you need to play by their rules.