Im 20 weeks pregnant and I want to stop smoking!?

Im 20 weeks pregnant and I want nay NEED to stop smoking. I know its a terrible habit especially while im pregnant, I have tried to stop numerous time before i found out I was pregnant obviously with no success, but now i have more of a reason to stop and I want to!! Im just wondering if it is at all going to be dangerous for my unborn baby, I am terrified of a miscarriage. Will the baby go into shock or have withdrawals? I dont want to loose a wonderful thing I have been blesses with before I get a chance to meet it! I dont need people to tell me that its bad, i know but i have heard conflicting things about people quitting and it going bad for the baby! Please someone help me!