^ so I liked your post, for lack of a suitable option... we need a hug, or a pat on the back option or something... because I didn't think sad was appropriate either.... we just need something fr solidarity or to show support... a flower? wont the sticks just love that.
OK big huge fellow mummy hug. Lets focus on the positives here.... she confessed, voluntarily... that shows she loves and respects you and you have an amazing relationship. It shows she knows she did wrong and you are going to love her unconditionally, regardless of what stupid thing she does... and at 18 the stupid is only just beginning. It shows she wanted 'the talk' and you to do the mum thing... she wanted to hear, that's how I started don't be a dipshit like me... she wanted to be reminded of that and she knew you would do it without making her feel worthless, COS YOU ARE A FRICKIN BRILLIANT MUM!!!!
Don't blame yourself at all either cos parents smoking making it acceptable for the kids.. I call bullshit. Neither of my parents smoked in my life time and both were militantly anti smoking (well mum would have a cigar when she was really drunk but that's it) and I grew up to be a minimum pack a day smoker. My cousins, who grew up with two chain smoking parents and all their clothes reacked of stale smoke cos they smoked in the house... both grew up to be militantly anti smoking. What your parents do does not control what you do.. were you in her mind controlling her muscles?, didn't think so (and if you were please tell me how so I can do that with the Kid). You did not put that smoke in her mouth, light it or drag... as an adult (18 is legally an adult) she chose to do that herself. As an adult, she knew she effed up and came to talk to you about it. You were a great example to her.