Until the end of your post where you lay out your actual dilemma, I could have actually written it; virtually identical relationship (with an engagement tossed in), identical friendship aftermaths, identical mixed feelings. It's unfortunate that he's not well, undoubtedly, but your responsibilities to him ended a long time ago. He's not part of your life now, you don't want him as part of your life now, and, as many previous posters have said, opening the can of worms probably wouldn't be worth the brief contact.