Wait, A-ko was doomed to hell because she took her own life, but not because she murdered B-ko?
And angels in heaven can smoke?
A-ko didn't intentionally kill B-ko, it was an accident in the heat of (a rather fucked up) moment. Had she gone on living, she could have sought out absolution and forgiveness and still saved her soul. Depending on the sect/denomination of Christianity, suicide can be, as mentioned, a one-way ticket to Hell and damnation, regardless of intention. I believe the logic is that, as sin comes from an obsession with the mortal world and where that spills over into harming others, suicide is seen as one refusing to face an aspect of reality in favor of removing oneself from suffering, regardless of how it harms one's loved ones, and thus is sinful without any chance of seeking forgiveness because, y'know... You died.
Personally I don't ascribe to the idea, but it is one perspective on metaphysics.
As for smoking, it isn't necessarily a sin, so I don't see why it would be an issue.
