I've heard that statement from survivors several times, and I assume it's fairly common. They don't usually mean they think they're insane, but rather that their lives don't make sense. They're confused about values and behavior.
That doesn't make them crazy, even though it feels that way. They speak of conflicting emotions and often of not trusting their perceptions.
Why wouldn't we feel strange or odd? When we tried to tell the truth, we weren't believed. Or we were told we were wrong when we spoke up. I remember quite clearly that before the old man molested me, I said to my mother, "You like Mel more than you like me." Mel was two years younger.
"I love all of you the same," she said.
As young as I was, that statement didn't make sense to me, and I knew Mel was the favorite. Years later, my other siblings and I talked about Mel, and they all agreed he was the favorite.
Because I wasn't believed when I made a simple observation, why would I expect my parents to believe me on something like sexual assault?
We're not crazy; we're hurting or confused, but if we persist, life will make sense.