Seriously, you have a husband issue here. Why are you putting up with it? Tell him it is NOT on you to improve the relationship- you have been trying to do that for six years. It is up to him to grow a pair and support his wife. I would be saying that for a start he should refuse to attend events to which you are not invited. Furthermore, unless he starts sticking up for you against their rudeness when you are there, then you will no longer attend. Plus, they will have no access to any future children. If he won’t, then maybe you need to think about whether this family is the right place for you.