OP you've got a problem, I know you have. This is nothing to do with religion, it's purely cultural, although some people (quite possibly your in laws) will tell you that it's your duty as a Muslim. That's because many, male of course, elders of the community will interpret verses in the Quran very, how can I put this, specifically! The woman must be meek, obedient, forgiving of anything her husband does, always put him first, and by extension his family. I read this:
Dear Madam! For the sake of your husband and for the sake of your own comfort as well as to find many good friends and supporters, put up with your husband's relatives. Do not be selfish and ignorant; be wise and do not cause your husband any distress. Be a good and devoted wife in order to be accepted by both Allah and the people.
Written by a man of course.
I've encountered this type of situation before, and you can't win without making a lot of personal sacrifice. Because whatever the Quran says, in that kind of blinkered, backwards looking environment, whatever you do you (with or without your DH) will be shunned and ostracised, not just by the immediate family, but the wider family and the community.
Because of the environment I worked in, many of the women who found themselves in the same situation did find the courage to say to hell with it. And they made a go of it and are much happier, even though they were cut off from any source of support (well, except me). Can you find someone who'll do the same for you? Because some of them didn't have the courage, and stayed, and are miserable shells of the people they could be.
From the ages of your DCs and his parents, you are still young. Nowhere does the Quran say that a DIL should be a slave. Please don't allow this to continue, don't live a life of misery. But truly, I know how much pain and suffering that bringing it to an end will cause you.
If my (somewhat lapsed) Christian thoughts and prayers mean anything to you, you have them.