getting off antidepressants/lexapro

How do you know you can get off antidepressants without relapsing into depression and horrible anxiety again? I have been on it for 6 years and been good for about 5 out of those 6. the only thing holding me back from getting off is the fear of going back to the same place I was in before I started taking it. I know i can wean down but what if even doing that causes a mental breakdown….