Obviously quitting smoking is the best for baby but you do it your way how your body can handle it. Sex is fine unless doctor says otherwise.
I would talk to your dr. You can have a lot of stress while trying to stop smoking. My coworker was told by her dr to taper off smoking.
I smoked for 10 years before I got pregnant and I quit cold turkey as soon as I found out. My doctor told me I did the right thing and now I'm 26 weeks and baby and I are perfectly fine. Your body will not go into shock. Continuing to smoke will do much more harm to the baby than quitting cold turkey ever could. And no you can continue having sex however you want unless your doctor says otherwise.
You should stop smoking asap the same thing happened to my step mom and she ended up losing it , so I would stop. I know it might be difficult but you want what's best for your baby
You should stop smoking straight away,your body will not go into shock...contrary to what some people say that 'its not good to go cold turkey while pregnant' there is absolutely nothing proven that goin cold turkey causes any harm to baby,im a smoker myself but always quit right away during pregnancy..try the ecig to help if your finding it hard its better than a cigarette at the end of the day...as for sex theres no reason to change what you and husband do..sex is perfectly safe throughout pregnancy unless told otherwise from a doctor