Husband smoking behind my back

My husband was a casual smoker up until we started trying for our first child (4 years ago). Since then I’ve been assuming he completely stopped and he says he did.

Well a few weeks ago after finishing from Uber, he came home at night smelling of cigarette. After I confronted him he said he didn’t, but when I kept asking he admitted he said and promised he never would again. Smoking is a big deal for me and he knows it. Well yesterday I went to his car to grab some gum and saw a cigarette packet with one cigarette missing. I’m very upset that he’s lied to me again and don’t plan on confronting him until I see another one missing. how would you feel about this and should I do?