Depending on the trouble you are having, you should start by talking it out with your spouse. Hopefully he is receptive to your discussion. If he feels protective, he could get upset. If he is receptive, ask if he will help you deal with the matter. If he isn't receptive at first, give him some time to calm down and think about it; he may feel differently later. You might ask his permission to speak together as a group, and set some boundaries. For example, if your concern is that his in laws are talking behind your back; let them know it concerns you and that you'd like them to speak with you directly from now on.
The best advice is to let each spouse deal with their own parents and family. Otherwise they feel caught in the middle and may just become defensive and withdraw. You promised to forsake all others and to leave your parents, so in theory you should always take each other’s side in a disagreement with in-laws. However, this does not always happen. Try to sit down with your spouse and discuss the matter calmly and find ways you can deal with it together.