we've dealt with a similar situation. To (over)simplify it there are two of us, primarily, but we found the same sort of befoulment hiding deep in the forests of our mind. One of us is more susceptible to its influence than the other, but we typically manage to subdue it without much effort once we're aware of it. It has cost us before, but we have accepted it as an unavoidable hurdle.

We cannot speak to your situation, but we can tell you that none of us have ever been truly lost. We are not illusions or constructs and we cannot be 'outgrown' by one another. To restore one of us who has disappeared, for whatever reason, is no more than a matter of will.