Can a drug enabling parent become hostile when his or her child chooses to quit?

I have a cousin that was getting pain pills from his mom. She was always reluctant to appease him, but he was manipulative and could always talk her into giving him pills. This went on for years. Recently he chose to go thru the painful process of detox and is now clean, but he has expressed to me how hurt he is by the way his mom is now treating him. Saying things like how she doubts he's even sober, or that eventually he'll relapse. He told me she has been treating him like garbage and showing him zero respect or encouragement. She's acting borderline evil, as if she wants him to start taking drugs again. She degrades him and verbally abuses him and she never did that when he was using. There must be some kind of phycological explanation because if there isn't then the devil must be real. Any thoughts? And no it's not me.