One thing I know is in-law issues, and it's hard because you want to say something but don't want to risk ruining your own relationship. It is a VERY fine line of what you can and can not say, because you are family, BUT you're not at the same time. I think I have seen my fair share of family drama and my parents fighting it out about them and now have dealt with it myself during my own relationship.
Depending on how long this has been going on, maybe it is better to walk away, give it time and deal with it when both you have the energy and strength, because really the stress could be doing more harm than good.
Do I hear you on the in-law issues. My friend's mother-in-law stole a set of our house keys a couple of years back (then lied and said his wife had given them to her). Then she lost them in an envelope with their address printed on it. Nice, huh??? When they found out what she had done, they had the locks changed and sent her a bill from the locksmith. She never volunteered to pay up the cash, but it sent the message that needed to be sent.
I can totally relate with you in-law issues. It drives me crazy that they don't listen to me at all when it comes to my child. My wife and I tell them every time we visit about our sons allergies and that the things they are trying to feed him will make him sick and every time they blow us off. We had to rush our son to the hospital when he was a newborn because he was bleeding from his rectum due to his milk allergy and still they try to give him milk products I understand your stress.
First of all, the Bible says that a man shall leave his mother and father and be joined with his wife. It sounds like there is some attachment your husband has to his mother that drives him to respect her desire over your feelings which is in no way biblical. While you cannot control what your husband does, and it sounds like you have been more than selfless in this situation, I would sit your husband down and get the deep reasons he desires his mother to be with you guys so much.
Invite them to come to your town and have lunch at a diner. Visit and let them go home. While I never had any in-law issues and never will they are both gone on to glory. Sometimes set up a schedule with both sides before you get married I know that the demise of all marriages are not always the in-laws fault. But its sad that the generation that probably endured the worst in-law issues themselves are passing on the cycle in the way they treat their children's spouses.
But unlike our parents generation who suffered through awful inlaws but felt they had no choice, our generation does have a choice. Sadly many sons/husbands feel the only choice they have is divorce. This is not true. To maintain the status quo leaves no one happy but changing it and finding joy does not mean you must leave your wife in the process.