I have been a caregiver most of my life. I watched my father get taken advantage of to the point of his death. Why is nothing being done?

I have read other stories similar to mine here. I was born when my parents were in their forties. I loved them so much. They were my whole world.
My older sisters did not have a very good relationship with them.
One of them disliked them to the point of cruel jokes.
They always came first in my life
They were good, honest caring people. My childhood memories are so good.
Later in my life I took care of my terminally ill mother for 3 years and held her hand as she passed. My father had Alzheimer's disease and dealing with the both of them for those 3 years was difficult. My sisters didn't come around much.
I never really thought about my father's money. Apparently he had way more than I knew. He was generous and non materialistic.
When my mother passed, he offered to buy me a home 2 doors down from him. I said that I already had a condo and he didn't need to spend the money.
In less than two months my entire world collapsed. This predator arrived and everything changed.
Everyone knew what was going on yet no one cared enough to stop it.
That was all I knew my whole life up to that point. I sacrificed my education and having a family to take care of them.
The locks got changed. Money started moving from his bank account to hers. (My mother and father were married over 60 years).
Many Family heirlooms were either thrown away or sold in a quick garage sale before my family home was sold and he was taken to another state. My poor father didn't understand the will and was very confused.
I was literally thrown out like garbage. The older sisters did not care at all. The sister that I was the closest to lied to me and stabbed me in the back. I was shocked. She is in my nightmares now.
I was told by an attorney that since he passed in another state, I would have to seek legal council in that state. (The will was made in my state) My father was very well known and several attorneys said they would have taken this on pro bono and would have won if he had died in my state.
I saw horrible physical and mental abuse towards my father, and towards me if I tried to come around. The police were called many times by my father saying she was abusing him.
I was horrified that almost NO one cared, considering it was so obvious.
My father, who served in WWII, and was very well known as an athlete spent his whole life providing for his family. He would have given anyone the shirt off his back.
I had been injured at work also during this time so that didn't help.
Moving forward over 20 years, I. still suffer from depression, Nightmares, Severe anxiety, OCD, paranoia, suicidology and PTSD. So many therapists, medications. Yet still, I have nightmares about 5 nights a week reliving the past. I have tried meditation and everything I had access to.
What happened to my wonderful Father was a crime, and I took it personally.
When my mother was dying, I sat next to her and held her hand. I remember her words. "I'm so afraid that someone is going to take advantage of your father and take everything", I just said no mom, that will never happen.
I suppose the reason I am writing this, which is very hard, Is I do not understand why the elderly can be so abused, and why nothing is being done about it.
I have left out names and so many of the events that happened and wish to remain anonymous.
I am in No Way feeling sorry for myself. I just wish I had grown up poor, because there was so much love in my family and this wouldn't have happened.
My life and all of my dreams were ruined. I am just trying to make the best of what's left of it.
I had a family, we loved dinners, birthdays, Christmas, Animals, get togethers, there was a lot of love there.
I am older now, but still very sad and angry. I pray that if just one person reads this and learns something to have a better outcome
It will have been worth it.
God bless