I am so sorry that you have had to go through so much. I really admire you for opening up on such a hard situation.
I have a really toxic sister that I had to block three years ago. Although my situation is NOT comparable to yours, I understand the hesitancy to forgive. There were times I felt like forgiveness was like a reward to my sister. She could hurt me and my family, and yet, she was still forgiven. Once I realized the forgiveness was for me, it changed my whole perspective and feelings towards her. I don't know if she will ever change, but I always hope for the best for her.