Yes they are super defensive. Mine has always been like this (think there’s something wrong there in his personality) but the drugs and drink make it worse.
Tbf, I think they do feel deep shame so anything that indicates we are calling them out on their usage and behaviour is going to garner that response/reaction. I know mine is ashamed – I think he’d be extremely embarrassed for anyone to know, which is why he’s not even been able to tell his favourite and trusted doctor. I have covered for him for so long but don’t even get any credit for that most of the time!