E.M.
J.,
From the information given, if you move in with your mother-in-law, under these circumstances, your marriage will not survive. I agree with the other women that you will be on her turf now and the problems you are having with her will only be compounded.
Your husband sounds like he thinks that since he is the one bringing home the paycheck, he makes the decision. It is your job to educate him that that is wrong. I can not even begin to tell you on how many levels counseling is needed for your family. Since your husband isn't listening to you, you need to find a way to work this out with out anger, arguing and separation. You left out any information on YOUR financial situation. So it is hard to give ideas. I am going to go on the premise that money is tight for your family.
Counseling help can come from anywhere if you have insurance for it. If no insurance there should be a community counseling center in your nearby area that charges on a sliding scale. It still could be close to $50 but if it gets you any help it will be well worth it.(I can attest to the fact that even just a separation can be quiet costly) If you or your parents go to a church, see if there is any counseling through that. Usually it is free for the first few times.
If you need to move, look into finding a less expensive place and give your mother-in-law the difference in rent. DO NOT MOVE INTO YOUR MOTHER-IN-LAW'S PLACE! I don't know your boys ages but you need to think of them as well as yourself. You will be with your mother-in-law all the time since you are a SAHM. Basically be open to just about any other scenario except the one your husband is wanting. But once you move in there you will be more likely to stay until you walk out.
Take this situation by the horns today, right now. Call around and see where you can get help for your communication with your husband. If needed, see if you can get financial help from your parents. If you have a checking and savings account put 1/2 to 3/4 of the amounts in an account for you and your boys. That may be extreme sounding but that will be the first thing he does to control you (removing your access to any $). You can always put it back once things are worked out. I know how easy it seems to go along with what your husband so get some help RIGHT NOW.
I could go on with more but I don't want to overwhelm you anymore than I already have. If you need any moral support or help finding counseling please contact me through email.
Hope this helps,
Evelyn