I felt (and sometimes still feel) that way. For me what has helped is seeking a recovery community, which I have found in my SA program. There are twelve-step programs for everything, so if you check out www.AA.org or www.NA.org (or whichever other program may be appropriate for your addiction: Resources for our recovery), you will find one.
The fear, for me, was when I thought about “all that time”. But really the sobriety is in the moment to moment, in the present. I have learned that (and am still learning) through my recovery work in SA, including my sponsor, and through my counselling.
Remember: it’s one day at a time. Reach out to the people who know the road, who have found recovery, and learn from them.