How do I go about a lawsuit against the VA Hospital?

I have such a long story. Before I get into this please know this is not about money, I lost my father, no amount of money would bring him back or heal the pain that I am in. What I desire most, what will make me feel better is justice. And at 26 I have now made it my mission to make sure that Veterans get the treatment they deserve.
My father passed away a few days ago at 58. He was in the VA Hospital for 8 weeks. He was a diabetic and a few months ago they found a narrowed valve to his heart. He was also on dialysis for failing kindeys. The reason he was there was because of Spinal infection.
Before the infection was found in my fathers spine, he has been to the ER 4 times. Each time he told them he had major pain in his back and side, and they just sent him home with even more medication and told him it was broncitis. My thing is, they knew he was diabetic, infections are common among those with diabetes, why did it take so long them to find that out. I feel like they were always eager to get him out, never did they truly listen,I was there, and I felt neglected for my fathers sake.
Second, while my father was in the ICU, we were suddenly told my father does not have long to live. And we were pressured my more than one doctor in a passive-aggressive way to pull the plug. One doctor had the nerve to come talk to my 19 year old sister who was visiting our father at the time and say “You know your father won’t get better. You know your father won’t make it” and I’m sorry, this doctor needs to be taught a lesson. For as much money as you make you need to take some classes and learn some bedside manners. We were already told my father would not make it, it was absolutely unnecessary to continuously remind us. They asked us to talk to hospice. They continued to ask “what would your father want?” And excuse me, I love my father to death and beyond, I would not want my father alive against his wishes. But they do not know that at the time, even though he had a breathing tude, he smiled at us, he held our hand, he communicated. He was able to feel happiness. And there was no way in hell that I would take my father off the breathing machine. They just kept at it.
So what happened was early one morning my fathers blood pressure got too low and he passed. My dads blood pressure had dropped before, they were aware of the problem and every time that happened, they would give him medication through an IV and bring it up.
So when this happened I was stunned. It was way too coincidental that he passed that day. Just a day or 2 after I signed a DNR. I only signed the DNR because I did not want my father to have his heart shocked. If God chose to take him, then he took him. But I did not sign a DNR meaning to not give him medication. I felt all along that they were trying to get my dad out of there. I don’t like it. It is a feeling in my gut, and I have great instincts. Anyway I have no clue how to go about all this. Like I said, the reason for all of this is for justice. Is for showing the Doctors and VA what happens when you mess with my Papa. Even though he isn’t here, I am! And I will fight for his name and I will fight for the justice he was robbed. I cannot save him, but maybe I can save someone else.
I knew my father was terribly sick. I am not naive, I did not expect him to walk out. But I also did not expect to be pressured to pull the plug. I did not expect to be wary of them and their intentions.

My father was hurt in the army years ago, and he has received free medical from them for years. I always worried that money played a factor as well.
If you have ideas for me, I would appreciate it. If you have negative comments please keep them to yourself. I just lost my father, the world lost a great man, of great humor, intelligence and spunk.