Limits on self-delusion?

Let's say that a person comes to suspect that a piece of information A is true but the person doesn't like the consequences of A being true. If A were consciously (and sub-consciously) accepted, that would precipitate certain changes in behavior. If instead, the person creates a self-delusion such that not-A is held consciously while A is held sub-consciously then the question is how long can this situation be maintained. I can imagine that the same changes in behavior might take place although they might take longer to occur. Due to the delusion, the person might not recognize that any changes were occurring or if they do might not be able to say why.