Once you quit you will learn ways to deal with life stress, instead of using smoking to hide from life's problems. I went cold turkey too because I wanted the nicotine out of my body as soon as possible - they say it takes 3 days for the nicotine to be gone. That doesn't mean your quit is done in 3 days - no. The mental adjustment is what takes the longest and the most work on your part.
As Doreen said. There's 2 kinds of stress. Stress caused by withdrawal and stress from thing that happen in life. You deal with withdrawal stress by quitting and going through the whole quit process. There's only one way to get there and that's to go through it. I used deep breathing exercises to help me relax when I felt anxious and stressed. Some use a cut straw like it was a cigarette and that is pretty much the same thing, breathing in and out. Jillar did something similar too - just pretended she was smoking a cigarette. She called hers Jillars Air Cigarette. It's all the same - deep breaths, hold & exhale. While you're doing that, calm your mind. Think of something that calms you mentally. That's one way to deal with stress from withdrawal.
Fear of quitting or not being successful is pointless. It is just keeping you from any hope of attaining your goal. You can't reach your destination if you don't start the journey. There's nothing to fear but fear itself is the way FDR put it I believe.