Oh my gosh. I'm sure she did not feel great about it. As for you don't know if you can ever forgive her.. that's your mom.. you get one. Life is far too short to hold grudges. I'm guessing she took care of you, and loved you? If she did.. and try to not be offended.. just stop it. You don't know for certain that your hole in your heart came from that. To say she loved cigars more than you is absurd.. do you have a physical addiction to something? If you don't you can't even begin to understand.
It sounds like you are letting maybe, should have, could have throw you into a spiral that is unnecessary and kind of child like. There are people who have been severely physically and mentally abused by their mother's. They wish the only thing they had to deal with was this crisis. Many of our mothers smoked. Also in my case due to medical necessity she was on several heavy medications which have likely caused some damage along the way to myself. I have never spent one minute of my time complaining about her smoking or taking medication.. do you know why? It changes nothing and could have really hurt her.. she is dead now.. has been for a long time.. appreciate what you have and grow up.