The OP is under an extreme amount of stress right now. It is impossible to live in the 21st century and not know that smoking is bad for you. No one is arguing that point.
In this case support and not pressure to add something as difficult as quitting smoking might be more helpful, since mental state has a direct effect on health.
Also, smoking affects circulation which can certainly relate to PN, but it doesn't sound like a causal factor in this case.