What Causes Sudden Change In Behavior During Last Stage Of Renal Disease?

Doctor my husband suffered from last stage renal disease. He was on dialysis for 7 years but the last two years his behavior towards the family was very angry, confrontational and seemed as if he stopped caring about anything. During this past year his behavior became so erratic, and confusing, where anything anyone said or did bothered him. He even began to argue with our 19 yr old constantly. We just could not understand it. I reached out to him many times and let him know we were here for him and we will deal with whatever he was feeling. My husband was a very proud man and I feel this sudden change in behavior was his way of preparing me that was not going to be around much longer. He passed away this December. Is this way of dealing with the fact my husband knew the end was near common. He knew he always had our love and support, we just want to understand what he was feeling. Thank you