I'm going to take a different tack on this one. He's hiding stuff ... but is it because he thinks it's 'wrong' or because he just doesn't want to hear about it?
Also, it's an addiction at this point, most likely ... he's been through a horrid experience (maybe not as horrid as some, but still not pleasant) ... and he at least thinks he derives comfort from the alcohol or tobacco ... it's NOT easy to stop an addiction.
I'm not excusing him. Just offering another point of view for what might be going on in his head.
My own father suffered heart attacks most of my growing-up years. All his brothers and sisters did, though his were the first serious ones, so no one knew about the family history aspect of it at that point. (He was the youngest of twelve.) He tried to kick the smoking habit, but he couldn't. Not even with using the patches and stuff. He knew he needed to, but his job stresses were too demanding. (Honestly, I think that's what killed him, more than the heart issues.) And so ... he died of yet another heart attack, when I was 17. It was not pleasant to watch. It was awful to attempt CPR on a man who'd just gotten back OUT of the hospital after open-heart surgery. He certainly never meant to do this to his family. (And the surgeon and nurses bear some blame there ... there were some less-than-proper care moments while he was still in the hospital, but that would be a longer story.) He was a good man and he tried ... not quite like what you're dealing with. But that was one addiction (his only one, that I know of) that he just could not break.
Even now, all these years later, I have absolutely NO idea what any of us could have done differently to help him. He would probably have been willing to try things, but I still can't think of anything that would have WORKED, going up against the stresses he had and all that sort of stuff. (Short of time travel and flat-out telling him what he wouldn't be around for, which we'll leave out as an option since it doesn't exist.) He would have tried ... but I think by the time we found an answer, his heart would have been too far gone. (Apparently at his last surgery, he should have been a candidate for a transplant instead of just the surgery.)
Some things a person has to do for themselves, and they have to find a reason within themselves that's worth fighting for. Some people can't find that reason. Or are afraid to look in case they can't find one. I mean, the way you've described him ... does he even HAVE a reason to keep on fighting? Can you think of a reason for him to keep on going? Life just to keep breathing isn't life, really. It has to be more than that ... and some people can't find that reason. Other people can offer reasons, but it has to resonate with the person himself or it doesn't count. And he doesn't sound like he's in a very stable place.
Sorry to go bleak on this ... it's not aimed at you, certainly. Just an insight into the dark places the mind can go, sometimes without even realizing how it got there, or that it needs to climb back out again. It's harder than chemo, radiation, and surgery all put together.