Many of us can identify with being scared. Not sure what scares you though. Some have already talked about being scared of the withdrawal process; I can identify with being scared about what life will be like on the other side.
That part sure was scary for me, questions about dealing with friends, navigating social situations, dealing with stress, etc. But if you stick it out for even a month you'll see that most is manageable. And beyond that it's not scary at all; it's eye-opening and you'll see life through a new lens.
As far as advice, the one day at a time approach really worked for me. Actually it was more like one hour at a time sometimes, but the point is to break it up into smaller increments and not look at the huge picture of quitting forever just yet.
Good luck and keep coming back here. This site helped me a lot and I hope it can help you too.