thelio, some of us win the family lottery, and some of us don't. Most people are somewhere in the middle. I'm at the extreme end, somewhat like you.
We all have to find peace with what we can realistically manage emotionally. If you feel you will be happier without the constant demands, and can withstand the possible loneliness that may result, walk away. It won't be easy, but it may help free you to fill your life with people who can give and take, instead of just take.
I wish you the best.
Dogs and nature abhor a vacuum.