I am in a somewhat similar situation as u. Juz that mine is solely in laws. I am guilty of venting on my kids as well.
So e husband went to tell his parents about the wrong n in turn, i was blamed for making him upset his parents.
Tat was a clear sign for me. Im taking a divorce route. It is not juz a easy way out but if your husband cannot logically stand in e middle to see the pic, then even when dis problem is solved, in e future u will have to repeat e same things for other problems.