Hi,
I take it you are difficult child's stepdad? My husband is also my kids' stepdad and I can remember having similar feelings as your wife at times. My husband had to bear with me while I came to the detachment process slower than he did. Also, I often felt guilty that he had gotten mixed up with such a dysfunctional family. He had been married before and had 3 kids of his own who all turned out to be pcs. When we married I didn't realize how awful things would get with difficult child 1 or how expensive she would turn out to be.
Sometimes it would infuriate me how calm and seemingly untouched he was by all the chaos too--like he didn't care.
So, I hope things get better soon for you--I think you are doing an amazing job and I hope wife comes around sooner rather than later!
Jane