My mother has suffered from diagnosed mental issues (bipolar depression, paranoid schizophrenia) ever since I can remember. She has called my wife alternatively to blame her, cajole her into "helping her (my mom) with something", guilt her into coming back. All despite repeated pleas to my mother to not interfere. A lot of my parents' marriage (they're not yet 50, I'm only 28) is based heavily on co-dependence, IMHO. It's something I'm trying to work through with the help of my IC.
My dad has got his hands full working two jobs to support my mom and my siblings. Honestly he has been helpful to help build me up but as far as how to heal the marriage, he has admitted that his advice probably won't apply here.