It’s a sad fact: The way to win what looks like undying devotion from a child (or a pet) who is totally dependent is to beat them up, then give them what they need – food and comfort and petting that passes for love. Do it enough times and the young child learns to do everything possible to win the approval of the parent in order to avoid the beatings and get what she or he needs to survive. The conclusion the child draws is the problem: The child comes to believe that it is only by currying the favor and pleasing their abuser that they will get any physical or emotional sustenance.
This pattern of behavior has become known as a “Stockholm Syndrome,” named after a group of bank workers who were taken hostage and paradoxically bonded so much with their abusers that they defended them against the police who were trying to rescue them. It’s now understood that this is a type of survival strategy. Bonding with their captors stopped the abuse while under their control.
These patterns are difficult to interrupt because the dependent person has little self-esteem and may believe that any difficulties in the relationship are her fault. Further, the controlling person may be a master at making threats and accusations that induce guilt and further the dependent person’s fear that she can’t survive without the controller. Because someone in this situation has internalized the dependence on the controller, the lack of self-esteem and the guilt don’t necessarily end with the controller’s passing.
You’re right that your wife needs help. She can’t get out of the relationship far enough to see it for what it is. I suggest you look for a therapist in your area who has worked with “Stockholm Syndrome” and trauma. I also suggest that you participate in the therapy in order to learn how best to support your wife as she struggles to withdraw from such a toxic relationship with her mother. It will be a struggle. Your love is tremendously important but it isn’t enough to combat your wife’s irrational fears of abandonment by her mother. Those fears were laid in early and powerfully. You need to learn equally powerful and concrete ways to show her that your opinion of her is more accurate than her mom’s. You both need to find ways to help her focus on the present and future with you rather than on her past relationship with a toxic parent.
I wish you both well.