Excuse?

Set proper boundaries and draw a line. If you can't help them, they are still humans on the same planet and live their first and only life.

Empathy shouldn't stop even if 'the worst kind of human' is getting electrocuted.

Well, I think people should go with their own judgment. Was a bad parent bad as a person or unable? Children who endure such an ordeal, as I once was, will know the difference. One of the aspects of enduring bad parenting is that one starts to doubt ones own judgment. Once all aspects have been weighed ones own judgment should be taken as accurate. Spouses of bad parents are very often quite blind to what is happening in their own house.