Heaven, increases all feelings to their extreme quality. Hell, decreases all feelings to their minimum quality. So if someone dies feeling sorrow, rage, hate and goes to heaven they’re going to feel all those to their extreme, that is why god creating hell is actually an act of love because he wants us to feel sorrow, hate, rage as little as possible and feel love to its extreme.
Good cannot exist without evil, though. And objective morality cannot exist without a law giver. At best, this is a paradox.
I’ve never understood the notion the good “can’t exist” without evil. I think it’s more likely that good can’t be recognized without evil as a basis for comparison. That doesn’t mean good things can’t happen unless there’s evil out there. I think they would just be seen from a different frame of reference.