Is it normal to continue to have such anger and animosity?

To make an extremely long story as short as possible, I am an adult female who was sexually abused when I was a small child by my half brother- who is now deceased. My father walked in on one occasion which stopped the sexual abuse from then on. My father never told anyone what he had witnessed and even though the sexual abuse stopped at that point, physical and mental abuse from this half brother, as well as another half brother continued on until they were old enough to move out. Both parents were fully aware of the physical abuse as it was not hidden like the sexual abuse- but neither ever did anything to stop it. My mother was also extremely physically and mentally abusive. She died in a car accident when I was a teen. I continued to live in the home with my father and older sister after my mothers death without any further abuse other than neglect from my father. As in neglect I mean his generally not being available to my sister and I. He spent a lot of time out with different women and wasn't home much- leaving two teenagers at home to basically raise themselves.
My father is now elderly and suffering from Alzhiemers Disease. For his own safety, he needs constant care to which I have him set up in a very nice (and expensive) care home. While getting his house ready to sell, my sister and I found many legal documents and other evidence that our father was NOT the man we thought he was. He had spent years and years lying, swindling and stealing from people- mostly family. For example; he convinced my deceased mothers sister (his sister-in-law to whom he never was close to- and he disliked for that matter) to let him be her legal guardian. Then he proceeded to place my Aunt in a nasty nursing home and rob her blind. He even made her change her will so that only he would benefit financially upon her death. Long story short, he has taken money that was supposed to go to his children and other relatives and kept it for himself. He bought himself a mail order bride with some of the cash he stole. She promptly divorced him as soon as she had her green card and took half the money he had in his bank account that he had stolen from others as well. (The money that was supposed to go to my deceased mother and aunts children- which he was withholding from us.) Through the years I have had many financial hardships i.e.; divorce, child with medical needs etc- to which my father never helped me with. Any time I asked, he told me that all money he was "holding for us" was currently tied up in investments- which was a lie.
I had eventually estranged myself from the entire family for years and moved far away. But when a sibling called and told me of his poor health and mental condition, I uprooted my family and moved back into town to help this man. Now that I am here and doing what I can to help him, and supporting him financially, I have such enormous amounts of animosity toward him. I regret with every ounce of my being that I even involved myself in this. I'm really having a tough time letting the stuff from the past go. Is it normal to continue to be so hurt and angry? And to harbor such resentment and animosity toward this man for all his neglect, dishonesty and greed in the past?