Quite honestly, she has to want to change.
She is not going to want to change, because as it stands right now,..she gets everything she wants. What motivation does she have to be any different ?
Right or wrong, she appears to be the puppet master.
As the outsider looking in,..this is not something you are going to be able to fix. This is a long-ingrained set up between the husband and the wife. It has to come from them; - the desire to change.
I am sure you have done the neccessary backflips,..and he has tried 'talking' to her,..and she has opened up here and there,...but ultimately, by your own story, things are the same.
Look after yourself first,...love shouldnt make you sick.