Is there a limit to what you should tell your psychologist without getting put into a psych ward?

Every so often I experience something that is obviously not real, but to me it is 100% real on every level. Like my aunt, who was right in front of me, saying something that there's no way she said. Or in class I clearly heard the teacher say something, I wrote it down, but after class I was talking to some students and they all looked at me strangely saying the teacher never said any such thing.

I was going to tell her but then it occurred to me that she might think I'm crazy, perhaps even fear me.