Just hunted out my Bible!
When I was a very young teacher, I taught a small nursery class in a special school for children with moderate learning difficulties and behaviour challenges. A little boy, who was living in a children's home, came to my class kicking and biting etc. Over and over again I sat down with him and said there was nothing he could do to stop us loving him, but I would be very cross when he hurt other people. He settled down quickly and became much happier, so much so the matron phoned in to ask what I had done with him! Unfortunately, at age 7 he was moved to a new children's home. The state makes a poor parent.
I have found it easier to see the person as separate from their behaviour. There is always a reason behind abusive behaviour, but abusive behaviour is never excusable. It is a choice, but sometimes people are unaware they have a choice, as they have not developed self-awareness. For example, some abused children go on to abuse as adults, while others do not. Some want to pass on their pain, others could not bear to inflict pain on others. It is never about the victim. I can forgive, but that does not mean I stay for the abuse to continue. If need be I walk away. I have a responsibility towards myself, because my well-being matters.