I have many thoughts I would like to share with you, but at the moment have the time to only share one.
I do not know all the elements of an Islamic marriage, but I thought you might be interested in one part of a typical Christian wedding ceremony. There is a line in it which many people think is old fashioned and often leave out -- "If any one has just cause why this marriage should not take place, speak now, or forever hold your peace."
It was created years ago to keep men who were travelling from having a wife in every town they went to, thus a person was to speak up if the knew the person was already married and about to commit bigamy. And many couples don't want the interruption that might be caused if a jealous "ex" was to crash the wedding. But, I usually council slightly differently when I have a party that considers leaving the line in. At the rehearsal for the wedding the day before, I turn to all of the family who has usually gathered for it, and tell them that if they really have anything against the marriage that the time to say it is before, not after the wedding. That after the wedding the chief repsonsibility and family connection for husband and wife is for one antoher. That from then on their families of origin need to take second place, and any comments that they have, no matter how they personally feel, need to be supportive of the couple. If they can't do that, then they should say so now. And if the couple goes ahead anyway, then they need to learn to respect that as well. For better or worse, it is the couples' decision to make, and the family's responsibility to always build them up.
Obviously, your mother-in-law never got the memo, I'm not even sure your husband did. Trying to correct this after the fact is hard. For that, my guess is that you are going to need some obective third party who can mediate a long-term conversation between the two of you, and who can tell mom-in-law to stay out.
I wish you luck.