I have a long marriage and a list of many things NOT to do-. I can't tell you exactly what to do ,specifically However,I can feel the pot boiling in what you have written.I think that if you just let the pot boil, you may lose your marriage.
IME, your family has to treat your H with respect.If they don't, you are abusing HIM by allowing him to be treated badly. It is an insult to him to allow him to be treated poorly by anyone.
So, if he is being treated poorly and you are not standing up and putting and end to it, he has a right to be angry at you.
It all rests with you. You are the connection between all the people. if you chose "not" to act, THAT IS an action. If you chose to just throw up your hands and say,"I don't know WHAT to do."-- that Is an action. You are not protecting your H.
One thing that I never "knew" was that I can extricate myself from situations. I learned that WAAAAY too late.Last year, I did not go to a wedding.I did not realize that I could simply extricate myself. I had to get sick in order to see this truth.
You are in charge of the situation.
I would ask myself,"Do i really,really value my H?" IF the answer is yes,I would allow ZERO abuse in any fashion by any family member to him.
That is how I see it. Any more info that you want on mistakes in marriage---i am your gal Love Ami