There is no "undiagnosis," unless you were given the wrong diagnosis in the first place.
There also is no cure.
So yes, you will have it for life. But, with therapy, coping skills, and sometimes meds, there is most definitely a way through.
Meaning that if you take care of yourself, you can have a "normal" life again. And that if you try and ignore it, it will come back to bite you in the arse.