I think these feelings are common. Part of it is denial, because we wish it weren't so, that it had never happened, and this is a way to try to minimize the experience in our minds. I think the other part is a heightened sensitivity to suffering of others. Throw in the entire societal attitude about mental health issues, how many people view it as a made-up thing, a slacker's excuse to avoid responsibility. These strands of belief all affect us, to the point we can buy into them and question ourselves.

Getting others to believe that what happened to you is "real " can be hard, and the closer they are to a situation the harder it is. Especially with something like child abuse. For various reasons. I know in my own case, I was the only boy and also much younger than my sisters. My father deteriorated mentally as he aged, so that by the time I was a teenager he was a complete brute. And, they were all gone from the house by then, living away and not seeing day by day what happened. And he hated me in a way he never did them, because I was male he viewed me in a way as a threat and rival and challenge to his authority and possession and control of my mother. And he made sure to take all of his psychotic rage out on me, far more intensely than I remember him ever doing to my sisters. That isn't unusual, it can go as far as one child being constantly bullied and abused by a parent while another is coddled - a condition which certainly results in radically different perceptions by siblings in later life.