MG, you are correct. Cirrhosis causes ascites, not the other way around. Ascites can be caused by any kind of liver failure. The fluids cannot be processed and they leak. Esophageal bleeding (referred to by Laurie) can cause death.
It sounds to me like he has a bit of mental confusion. Whether that is from any kind of encephalopathy (my husband's encephalopathy cleared up over the course of a couple of months or so) or whether he is just overwhelmed and scared and not hearing things correctly isn't clear.
If he will permit you to sit in during a meeting with the doctor, you might be in a better position to ask the necessary questions. They may not know a lot of things for sure, but you can ask what they suspect and what they are basing that on.
There is a ton of info on the web about liver disease.
I know he's an ex, but as you said, he is a nice man and your daughter's father. I'm glad you are able to support him a bit through this. Just remember to take care of yourself, too.