Florence,
I can totally relate. Somehow my brother learned to take care of his body (I would eat junk to deal) and not be affected by all the craziness of growing up with my emotionally abusive dad. Where as I learned life was miserable and happiness was only to be found in periods of escape.
One thing that has really helped me is becoming 100% financially independent from my parents. for you maybe having a great babysitter too.
Hoping you peace and don't forget you are with it just because, regardless of all the history and insanity.