Smoking while pregnant

I'm 16 weeks and I used to smoke. But haven't for 16 weeks. Well tonight one actually sounded good...like the taste and everything 😷. 
So I had one. I read that just one isn't going to do any permanent damage. Is that true? I only smoked half actually. I know people who've smoked their ENTIRE pregnancy like a pack a day. 🤐 
Update: Thank you all for your support. I am 100% against smoking while pregnant. But I gave in. And I know it was wrong. I think baby is okay, I prayed afterwards for strength to keep going on without one, and to keep baby healthy even though I stumbled. I can do this. I know it. For some reason though...it sounded so good. NOT ANYMORE. I was wanting to quit even before I was pregnant. So hopefully these remaining 5 months will be the push I need to make it the rest of my life. I want to be healthy for my children and be an example.