Depressed and desperate, need advice

I'm almost 20weeks pregnant and still smoking cigarettes. I feel awful. I had absolutely every intention of quitting as soon as I found out I was pregnant. But then I got sick and have stayed sick, constant morning sickness all day every day. I have no social circle in my town and my husband works a lot. I can only see my doc when I have an appointment, he won't see me otherwise because he says there's nothing he can do for me, my pregnancy is normal. I'm not showing, I just look fat. 
I'm so depressed and lonely and cigarettes are the only thing that helps my anxiety about this pregnancy and all my fears and doubts. I keep reading people's comments that if I can quit smoking for my baby I shouldn't be a mother and they're right- I shouldn't be having a baby if I can't keep it healthy. I've tried all the stop smoking devices but I can't quit. I never thought I would be this person and I'm ashamed. I keep having dreams of people coming to take my baby away because I'm not fit to be a mother. I wake up and have a cigarette to calm my nerves. What is wrong with me??