I've read quite a few online things about it and, from what I can remember, child abuse (I'm talking emotional abuse here but physical abuse probably causes these things as well) just lends itself to mental health problems later in life eg depression, anxiety, low self esteem, potential eating disorders etc
And I suppose a child who has suffered abuse will think it's their fault and, what hurts is, you probably love your family and want to be involved in their lives, but perhaps you're also left feeling that you don't want anything to do with them? You think these people are toxic and not good for you mentally, but they're the only family you have so you have to/want to be with them?