In laws issues is one of the gravest problems you face in your married life. You can neither thrust them away from you as unwanted nor can you bring them into your life as most wanted. Your relationship with your in-laws will be tolerable only when you live away from them. Are you living in a joint family? You do not have enough privacy to truly understand your husband. Talk to your husband in a reasonable manner that living seperately does not mean he is ignoring his parents. Do not think in laws problems will affect your relationship with them only. It will slowly make inroads into your relationship with your husband also.
If your husband is not supportive, you will have to decide whether taking matters into your own hands is a feasible option. You may try gently letting your husband know that if he is not able to support you, that you plan to talk with his family yourself. Ask for his thoughts and whether he wants to be present for the conversation. That way, if it explodes, your bases are covered. Your husband cannot fault you since technically you obtained his permission. The other option is to seek out a qualified marriage counselor and talk with him or her about the issue. You may feel better simply getting it off your chest, and he or she may have some advice that does not involve an awkward and potentially ugly confrontation.
Perhaps if you have a decent relationship with at least one of your in-laws maybe you can approach him/her personally. I ended up having to talk to my mother-in-law alone about a matter that was becoming an issue for the whole family. I thought maybe she would be able to stand by me even if her husband oppossed. It was not easy, but I had to take that chance. I hoped she would be able to talk to me, woman-to-woman. In the end, I think it softened her a little bit. I think it makes a big difference in terms of how you approach them. I went to her and told her that I needed her help. I didn't try to blame her or her husband for our troubles. I think this was a smart approach.
Howell, you must work together with your husband so that you are both operating on the same side. If the issue is serious he needs to understand the gravity of the matter and step in. It will be better for your relationship in the long-run to work together as a team even if this means upsetting his parents.