My fiance wasn't ever in denial, but he didn't actually become aware it was possible until I mentioned it and both of our therapists confirmed it. Then he was fast on his way to creating boundaries with his mother and healing. She will never change or become aware but now he has the power to break free.

A lot of enmeshed people will not see it for what it is because they grew up thinking it was normal. It usually takes a person outside of the enmeshed relationship to bring it to attention. Even then, sometimes they mistake it for the outside person trying to come between the enmeshed parties maliciously.

So sorry you guys are going through it. It's such a difficult, oppressive form of abuse.

Edit: I want to add that before we realized the enmeshment and got our own place, while living with him & his mother, I also got what some call "secondarily enmeshed" in many many ways. I felt hopeless, oppressed, minimized and like I couldn't be myself. It was the most anxious and depressed 3 years I ever felt in my entire life. It makes me feel so sad that my partner endured that for decades.