I have seen D in my family and I can understand how you feel. Yes, sometimes death is easier. I've thought that many times.
I do think this book may help you. It's for all kinds of grief.
One day you will come to terms with your feelings. But don't compromise yourself and your values to make someone else feel better. If nothing else your Dad has to respect you and your values.
You are a good woman. You don't need to leave to enjoy your family.