Daugher is dating an alcoholic
You might have become angry and aggressive and threatened to cut off support.In exasperation you might have told her she’s stupid, obviously can’t think for herself and you might have confronted him.
Or, depending on your intuition — you can say it directly and explicitly.
Unfortunately, when you’re dealing with a coercively controlling person, they believe they are always right and are driven to get their way at all costs. And she manages this whilst also dealing with his tactics that have distorted her reality and perspective.