Do I have a defamation case if the doctor and nurse accused me falsely?

My brother was in ICU for almost 3 weeks and died the second day he was there. I was accused of giving him water by the doctor and nurse. They were not in his room, just my brother's wife and father in law and they even told them I did not give him anything. They still accused me and even said that if something happens to him I would be responsible. The problem was the nurse swabbed his mouth. He began to choke and the nurse failed to suction him right away. My brother's health went down from there and he died almost 3 weeks later. I went to medical records to get copies and didn't really read through them until the other day and noticed they said I gave him water then on another page it said I swabbed his mouth then the end of the report it said code started then family decided to stop. I was the only one there as far as family and I did not tell them to stop matter of fact I told them not to.