Terra isn't slamming Amy. She's just letting us all know in a darkly humorous way what it's like being in rehab. She knows full well from experience that Amy's mind won't be wholly receptive to rational thought just now - there will be a need to try and maintain some dignity, some grabs for independence in what is bound to be an experience lacking in both. As for Terra being jealous of Amy - I've never known her express anything but admiration for her as an artist.