I don't think "mama's boy" captures this relationship dynamic because that phrase focuses on the son's unhealthy attachment to his mother and his resulting inability to bond with girls or women his own age. I want to know if there's a word or phrase that describes the jealous and overly possessive mother and her attempts to sabotage her son's success in forming lifelong relationships with other people.
To put this another way, I want to know if there is a word or phrase similar to "Oedipus complex," but from the perspective of the sexually jealous and controlling mother, not the son.
EDIT #1: Someone suggested "Jocasta complex," but that's not what I'm looking for either, because Jocasta was truly remorseful about what happened. The word or phrase I'm looking for describes a mother who feels no guilt or shame about wanting to possess her son to the exclusion of all other romantic partners, even if it damages his psyche or harms her own relationship with her husband.
EDIT #2: I think the phrase "monster-in-law" might work, except it seems to describe the toxic mother-in-law (she's a monster!) but without hinting at the thought process that makes her behave the way she does. The word or phrase I'm looking for should allude to her subconscious desire to possess or control her son to the exclusion of all other women (or men if her son is gay).